Please everybody send this guy more money so he can keep doing this for us. This guy knows more about the history of colt and firearms than anyone else I have seen.
@@Torqd_Off Yes. Gun Jesus from FW repeats historical information without having lived or personally experienced that history. Though I enjoy watching him, he often has little or no context because he knows nothing about manufacturing or world-level marketing, combat use of these types of firearms. This man has lived much of his information or at least worked very close to it.
Great video Mr B! There was a lot that I didn't know about the Colt external piston saga. I agree with you about the fact that it was a mistake for Colt not to release their piston guns when they had the opportunity. They played right into the fact that the public were beginning to dislike the air of superiority that they maintained. Resting on their laurels and refusing to adapt to the market. I'm a firm believer in the fact that the original internal piston/DI design is just better overall for the AR platform, but sometimes as a manufacturer, the best thing to do is to give people what they want at the time.
Its funny you mentioned the HK smear campaign. I remember all of the hk 416 hype in the tac rags 11 or 12 years ago, waaay waay over rated just like the scar.
Yeah you still see the effects of that smear campaign. Everyone today knows that was the gun that capped bin laden and it’s the weapon for tier 1 groups like delta, team 6, and hrt etc. but they’re not amazing weapons. Barrel life is fairly short and it’s a very limited system. Lmt and lwrc imo make a better piston ar
Yea haha I still remember as a teen seeing articles or videos on the xm8/416/scar and how they were sooooo much better than an ar15 that they were practically saying the army was negligent for not leaving the m16/m4 and upgrading too them. Made it seem like they were the toughest rifles on earth
Excellent information I have not seen this before..I can't believe I missed this..I still have that Rhino conversion system from the 80's.I talked to the inventor back then at the time and he stated they had problems with the return spring compressing in the gas block because of all the heat..
Thank you so much. You do a great service to the firearm and history communities. I would wager that your channel is the most BS-free firearm channel, not just on YT but in all of the internet on any platform. Thank you sir.
Would love to listen to SAS & The School of the American Rifle talk about AR's. Not sure who's got the most knowledge of an AR15, but they both can go deep into the system.....
Amazing video! Very glad that someone has finally addressed the upper receiver / cam interaction wear that has been bugging me on the piston AR's for about 8 years! I own a few PWS (primary weapon systems) long stroke piston guns and they all have it. PWS claims this as "normal wear" and will not address it.. Seeing as they copied a lot of colt's design, I am surprised that the metal plate in the upper receiver mod did not get carried into the PWS MK models as well.. cost savings of just using a mil-spec receiver I guess. You mentioned that this wear would cause problems so interested to hear about those if you could elaborate.
It's great to hear straight forward information without ego being injected.Especially considering your vast knowledge on the platform as well as actual hands on experience from years of work and dedication. Thank you.
Thats funny. I just read an article by a former green beret on how the Ar15 wasnt a good prepper rifle. He refrenced that 2007 test. I called BS. Thanks for vindicating me. All my ar15s work great in sand,dirt,and mud. Like I commented in the article as ling as its not an old clapped out rifle they are gtg. I may be wrong but i think the DI system is better for dirty muddy conditions because it blows debris away from the ejection port.
@@bobbyraejohnson yes. The piston system is good if your a tier 1 operAtor who lays down heavy suppressive fire on the regular. For my needs a DI is just fine.
Those tests had a flawed premise, as well. Most of those rifles were full auto. The M4 use a cam-based burst trigger. Meaning, the cam has to cycle three times before it will reset, so if the bolt locks back before it cycles all three times, it will only cycle the remaining 1 or 2 shots, then reset. Every time the M4 failed to fire all 3 rounds, it was counted as a malfunction. Paired with old, used magazines, and it's obviously nothing more than a shakedown.
Its mind blowing that Colt sat on the best technology and decided making a profit was *NOT* worth their effort. I always wondered why they didn't offer a piston upgrade to existing M4's in the mid 2000's since they had all the military contractors all they would have to do was offer cheaper upgrades to existing inventory and offer to produce the piston going forward and they could have kept Military contracts for another decade or more.
A lot of great information there. I was able to follow along with half of what you presented here and you answered some questions in my mind, but I will admit the other half just blew me away and was over my head. I think I will watch this again and try to gain the knowledge that was over my head. What a great resource you are to these platforms. I wish you the best and will use a phrase that my Dad used when he was a live and he would say (you are a true gentleman and a scholar)
That gas piston design, with the "thermal expander" also is there to reduce stresses on the bolt and lower receiver's bolt guides, due to the piston op rod hitting the bolt at an "off dead center angle" (the top of the bolt), which causes the forces of the action to want to force the front of the bolt up and the back down, as it slides back. Having the front of the piston able to flex, allows those stresses to dissipate before reaching the bolt, leading to a much more linear and gentle push rather than slap.
Why would a gas impingement system work any differently? The gas from the gas tube also hits the gas key “off dead center angle”, putting a similar torque on the bolt carrier, pulling up on the bolt head and pushing down the rear of the carrier.
@@5133937 Are mistaking a true gas impingement with a DI-Inernal Piston in an AR design? On a true DI yes, you're correct, the forces and the problem is the same, even on long stroke guns like an AK, but on Stoner's Internal Piston design, the gas is bled thru a tappet, which you might think is where the forces are applied, but there actually routed down behind the bolt, forcing the bolt and bolt carrier apart, which unlocks the system. Those forces being applied directly behind the bolt face, inline with the barrel, imparts far different stresses than slapping the top corner of the bolt carrier.
That Colt "M16A2" looks a hell a lot like a South Korean K2, externally and internally. Really, just the bolt assembly and recoil spring seem different.
Give customer what customer wants. That's the mantra of any business that wants to get more clients. The delay in delivering what customer wants costs money. Russians had even re-designed the AK-74 to feature picattini rails and the result is AK-12/15/19 for military sales. Civilians get that and even more crazy, a split-receiver with a left-side charging handle in AKV-521. But while Izhmash could be forgiven for lagging in this (post-breakup economic difficulties and national gun laws), Colt did it all to itself.
imagine having this wealth of knowledge, and obvious critical thinking skills, and tech know-how, and the communication skills to explain these concepts, and then working for the Zap Braniggans up at Colt who just dont want to hear it.
JustAnother InternetExpert i have a Mega Maten with the MML handguard system. I think it’s better than a one piece. It’s just as rigid, but much easier to work on, should you ever need to. Mega’s one piece was called the Megalithic.
Hi Chris, Have you ever seen a Factory Colt AR (any model) that carries the name 'Commando' machine inscribed onto its Lower Receiver? Thanks, Bob. Appreciate your in depth analysis of this weapon system.
MrRmh3481 I’m not Chris but you certainly can buy the Colt 6933 SBR which has “M4 Commando” on it’s lower receiver. It’s actually still in-stock at ArmsUnlimited.
I wonder if you can show how to do a barrel swap on the LE6940? Another question, The direct impingement model, can it be changed to a piston version with aftermarket parts? Or even Colt parts, if available??? I've got one that I use as a every day use rifle. I've changed out a lot of the Colt original parts and have them put away in case I ever need to sell it, but I wish I could change it to the piston version.
hmmmm my m4le 12" has been topped with a PWS Diablo gas piston system now for the past 15+ years and shows absolutely no wear like you mention at 29:45. is it a possibility that by securing the piston rod to the bolt carrier eliminated the flex or jump?
Chris, are the 2007 Dust Test reports available for us to read online? Did they use MIL-C-71186 for the tests? Is there an anti-tilt pad on the bottom-rear of the bolt-carrier of the LE6940P? Is another reason for the articulating rod on the LE6940P to allow the operating rod to alleviate some downward force on the carrier and reduce carrier tilt? Thank you for making clear that the AR-15 is not DI (e.g. AG 42, MAS 44, LR-300, etc). I've struggled with nomenclature to describe it, but I like yours, "Internal Piston."
Very interesting. I end up wanting to hear your overall conclusion/opinion about these systems. It seems clear that you think criticisms of the so-call direct gas systems is overblown, but I'd like your final word: would our armed forces be better off if they switched to an external piston gun? If so, which gun or piston system do you think has the most promise? Big question, I know, but I get the feeling you would have an interesting answer.
Thank You for sharing some of your knowledge and telling us some little know history of this epic weapons system! Seems like Colt became a victim of their own arrogance.
I already commented on this video, but here’s two more questions… I have an LE6940 & I put Troy Industries Battle Rails on it, they’re just about the size of the Knights but available and probably half the price. What I’m wondering is if you think the Manta Low Profile or Wire Management rail covers, even Daniel Defense rail covers feel smaller, better in your hands than the Knights, Troy Industries rail covers??? Cuz I think the Troy feel big in my hand… I saw you had both types on your rifles. Other question… I saw you had both Vltor and Rodgers Super Stock on your rifles, also. It’s hard to determine on video if either one is longer than the other. It appears that the Vltor is shorter. I’d love to know if I could put a piston system into an LE6940
Chris, I have a Colt 6940P "Piston Carbine" complete lower. With the price and lack of availability of the 6940P upper on the secondary market, I have a question regarding the standard 6940 upper. Do you know if I would be able to purchase a stripped 6940 upper ($499 @ Brownells) and build it with a Superlative Arms piston kit? I'm mainly just curious if the OP rod would fit into the receiver. I assume it would but I've never seen a 6940 upper in person.
@@SmallArmsSolutions yeah I'm kind of thinking that I should just wait to find the correct 6940p upper and just buy one complete. If one ever pops up for sale at a decent price
SmallArmsSolutions I get it. But it just looks dumb. I love the fact Pws has full length rail. Lwrc also made theirs longer with the ic-a5. Both better piston rifles
To each their own. But I think adding more weight (via a longer rail) for no functional reason is dumb. Doing anything just for looks on a battle rifle is dumb to me. I’ll take the lower weight over looking cool any day. But hey, if you’re really into looking cool, I’m sure there’s an Airsoft gun out there for you.
Trey Gregory a longer rail gives you more space to rest your gun on barriers to take shots without resting it directly on the barrel, avoiding a change in point of impact.
You talk a bit about the cam pin causing damage to the receiver, I've also heard this noted from others as well. I understand how the system works however I feel as though I am missing something. I am no expert so pardon my ignorance but why does the cam pin have the large head on it in the first place, especially if it runs the risk of causing damage to the receiver?
I would think that the square head keeps it from falling into the carrier, or maybe it's baring surface is more for alignment so it doesn't fetch up in movement. Not sure
I believe he broke his back at one point and this is a brace. It's an older video, from not long after he started his first channel (which was deleted).
So, the AK uses a superior gas system? I say this hesitantly because of the mention of an AR piston system needs to be overgassed... I wonder what the difference is with the AK that makes its system different?
@@GunFunZS At close range where most of actual assault rifle killing takes place (well-inside 200m) 7.62x39 is a very potent cartridge with a heap of "thump". With a 200m zero the bullet climb out of a 16.3-inch barrel is maximum 10cm inches at 100m, so it's pretty good for most real-life engagements. Even US military concedes that at 200m a 5.56mm M-16A2 has a hit probability of ~20% due to battle stress. Optics help, but there are other nuances. Today most body armor will stop the old M43 7.62x39, but then it's a standard copper/lead bullet. If we were to make it in a same construction as Russian 7N10 or US M855A1 it'd have good penetration too. At the time 7.62x39 was more impressive comparing.
I am def sharing this. About 0 people believe me when I tell them the AR-10/15 gas system is an internal long stroke piston...nor a delayed gas impingement system instead of direct impingement which means the gasses pushes directly against a flat surface .most piston systems use direct gas impingement to push the opp-rod/piston. Osprey defense pistons use a delay in the form of a gas expansion chamber type piston and gas cup on the opp-rod. It's my personal favorite short stroke conversion. Anyway Colt wouldn't call it an external piston just because. It would simply be called a piston system. The need to specify hints at the fact there is already a piston,and they are changing it's position from internal to external. Sorry to rant my brain goes Into overdrive when I listen to people who actually know what they are talking about.
Beach&BoardFan u It is a back brace. Sometime in 2016 Chris fell off a latter or something and broke his back. Many videos on his old channel( prior to being banned) in 2017 have him wearing this back brace.
@@SmallArmsSolutions Understandable. Would you ever allow someone with extremely precise measurement instruments to measure it down to the finest detail so others could replicate it and fire a copy?
Specifically, what is an external Piston external to? And, what is an internal piston internal to? They’re nonsensical terms. Prove me wrong. It’s as bad as, “My pronouns are…” What is opposite of direct impingement? I’d say indirect impingement. But I’m a conservative. You get Chris Sirois on and laude him for his achievements to include the Sig 516 and in other VDOs you claim the Colt M4A1 is top dog. It begs the question, “Why isn’t Sirois designing Di rifles? Because he refuses to believe contaminating lower receivers and BCGs with debris is an ingenious design strategy. Internal to the BCG makes it external to the gas block. If you’re going to double talk and manufacture obfuscatory nomenclatures, go help Greta Thunberg with climate change. I love ya Bartocci but clean it up.
Dude, you lack any form of mechanical understanding. The M16 is not direct gas impingement. You can look it up! It is a piston made up between the bolt and carrier, hence internal piston. External piston means the piston is locates outside the receiver and on the gas block. If you lack that understanding, nobody will help you. Im curious as to what your experience is? I doubt you have worked in this industry and watch to many RUclips experts who have never worked in the industry. Also, the military never referred to the M16 and direct impingement. Some uneducated moron just came up with a wrong reference name and it stuck.
@@SmallArmsSolutions • Gas-operated (Expansion of gas within piston inside bolt carrier), closed rotating bolt. Alright Mr. Bartocci, tell me you didn’t add this to Wikipedia. Nobody else is anal retentive enough to do it but you. Tim from MAC but he’s not that familiar with sophisticated nomenclature. You already conceded its generic operation is termed Di, for good reason I might add so, I will stipulate it is indeed a Gas-operated (Expansion of gas within piston inside bolt carrier), closed rotating bolt. Give me a break Chris, I’m retired from a major airline. I started on fighter jets in 1978 at McClellan AFB. I’m a licensed aircraft mechanic since 1983, though, licensed too is a generic term. It’s more correct to say I hold a DOT Mechanic’s Certificate with ratings of Airframe and Powerplant. That’s a mouthful. That’s why Di and piston are used and not bombastic language and to some, as in your case, obfuscatory meanings. I say that without reservation or compunction because direct impingement is a type of gas operation for a firearm that utilizes gas from a fired cartridge to impart force on the bolt carrier or slide assembly to cycle the action. You always say, “I know some will disagree with me - put it in the comments.” You’re a great teacher Chris and a great man. We just don’t agree. No disrespect directed to impinge upon your persona.
Stating facts is not being anal, it’s being a professional. One who has worked in this industry. You are good spreading misinformation, good for you. Direct gas makes no use of a mechanical piston. MAC is professional, he spreads proper information. Im not here to convince a closed minded individual who ignores facts. If you dont like my approach to my profession, there are many hobbies run channels you can watch.
@@SmallArmsSolutions • You ignore the fact I went on record and stated you were a great teacher and instead focus on my contentions. If calling it an internal piston gets it for you and Tim, then rock it. I watch all of Tim uploads as well as yours. You are both quintessential professionals. That doesn’t mean I agree with every jot and tittle. It does mean you don’t start every VDO with a sophomoric vaudevillian skit. Professionals use both operating systems • that doesn't mean one isn't superior. If one system can adjust for climatic conditions, a variety of ammunition, and suppressor use, it's a no-brainer. Di supporters are analogous to climate change activists; they believe in something manufactured that only exists for those in the swamp that can profit. You’re brainwashed like a liberal. If you can’t wrap your head around the 3 reasons I just stated, you’re loyal to a tainted cause. Why isn’t Sirois designing über internal pistons? Di’s are so janked they’re manufacturing adjustable gas key/gas paths. I can only laugh and applaud your devotion to Mr. Stoner. Adjustable gas paths are inane when compared to an adjustable gas valve. Chancing polluting the lower receiver is inane. Which one of us is disseminating misinformation? This is where you shine because you have inside knowledge. I don’t know if the following are true but I would trust YOUR information. The SIG MCX rifle has been used by various militaries and SWAT teams, including the Ukrainian Armed Forces and the U.S. Special Operations Command. The MCX-SPEAR/XM7 has also become the new standard issue rifle for American soldiers. The British police and SAS troops also use an older version of the SIG MCX called the Virtus. I don’t expect a reply, I cut deeply on this response; didn’t leave you any wiggle room. If Sirois won’t tell you, I will.
You have obviously no experience with internal piston rifles, at least none in the real world. You dont understand the mechanics and not even the history. Chris Sirois is a friend and colleague and we have worked together on a few designs. Im also guessing you’re not a veteran who has used these systems. Each has it areas where they shine. Your misguided opinion is based on commercial rifles build to no military standards. If you understood when tests these guns go through and pass you would not make such misguided statements. I am very familiar with what the Ukrainian Army uses, I have worked over there 3 times. You? I have spent a significant ammount of time at Fort Benning and Bragg with SOF. Have you? M4A1 has been most of their weapons of choices. I have also took part in weapon replacement programs all over the world. My guess is you have not. You have not see these different platforms compete head to head. The external pistons shine in short barrels, short barrels suppressed, over the beach and bore obstructions. The US Army has been very pleased with the performance of the M4 which is why it’s still in use. None of these other weapon have offered anything significantly better. Most of the people who speak as you, are people who are tinkerers, buy substandard components and often done know how they go together. Sometimes you need to keep your ears open and mouth shut and listen to those with experience. I fully state in several videos where certain weapon exceed some of the parameters of the internal piston. Those generally are limited SOF situations. Chris Sirois and many other engineers will tell you the same. Chris has not messed with internal piston because he was asked to build external piston guns. For military contracts, there is not really anyway to compete with Colt, LMT and for some small part KAC. Chris exploited the strengths of external piston and went in that direction. Same as many other companies making external piston versions of the M4 (HK, Caracal, Beretta, LMT….). Military weapons are not meant to and should not have adjustable gas systems. Suppressed and unsuppressed if the system is not balanced for both. Internal pistons do not require it in military weapons with military ammunition. If you understood engineering and Military-Spec, you would understand that the weapon is designed around a specific round with a specific propellant which has spaced out chamber and port pressures. You dont need adjustable gas for this. In the commercial arena where you have ammo all over the spectrum, there it becomes a balancing issue. I dont expect a response. This is a. Sharp dose off reality of this industry and the mechanics and how weapons are designed. Which isn’t clear you have no understanding of. I try to educate people on the right points. But there are some people out there, you cant teach them a thing. They are so caught up in their own head that you could show it right to them and they would disagree.
Greetings…off topic info request. I recently purchased a 6940P. Any suggestions on obtaining an operator manual? Thanks for any help you can offer. Steve
Please everybody send this guy more money so he can keep doing this for us. This guy knows more about the history of colt and firearms than anyone else I have seen.
Even the Gun jesus, forgotten weapons???
@@Torqd_Off pretty much same level, he has extreme AR platform knowledge along with the brains to build and assemble them, from scratch if necessary
@@Torqd_Off Yes. Gun Jesus from FW repeats historical information without having lived or personally experienced that history. Though I enjoy watching him, he often has little or no context because he knows nothing about manufacturing or world-level marketing, combat use of these types of firearms. This man has lived much of his information or at least worked very close to it.
Chris is a walking history of Colt and has a ton of knowledge of other firearms manufacturers. Such a huge resource!!!
I have a Colt 6940P, truly a hidden gem
Greetings,
Do you know how I can obtain and operator manual?
Thanks,
Steve
The breadth of knowledge you have of these subjects is impressive (to say the least).
I love these technical and historical videos of his.
PWS makes this exact same gun a long stroke AR-15 it's actually pretty nice.
Great video Mr B! There was a lot that I didn't know about the Colt external piston saga.
I agree with you about the fact that it was a mistake for Colt not to release their piston guns when they had the opportunity. They played right into the fact that the public were beginning to dislike the air of superiority that they maintained. Resting on their laurels and refusing to adapt to the market.
I'm a firm believer in the fact that the original internal piston/DI design is just better overall for the AR platform, but sometimes as a manufacturer, the best thing to do is to give people what they want at the time.
Its funny you mentioned the HK smear campaign. I remember all of the hk 416 hype in the tac rags 11 or 12 years ago, waaay waay over rated just like the scar.
Hype sells...
Yeah you still see the effects of that smear campaign. Everyone today knows that was the gun that capped bin laden and it’s the weapon for tier 1 groups like delta, team 6, and hrt etc. but they’re not amazing weapons. Barrel life is fairly short and it’s a very limited system. Lmt and lwrc imo make a better piston ar
@@jaydubs6354 they sure do ! 416 was dumped just like the scar !
HK in general is really over rated, and are an absolutely terrible value on the market lol. You can get better guns for cheaper.
Yea haha I still remember as a teen seeing articles or videos on the xm8/416/scar and how they were sooooo much better than an ar15 that they were practically saying the army was negligent for not leaving the m16/m4 and upgrading too them. Made it seem like they were the toughest rifles on earth
Excellent information I have not seen this before..I can't believe I missed this..I still have that Rhino conversion system from the 80's.I talked to the inventor back then at the time and he stated they had problems with the return spring compressing in the gas block because of all the heat..
Colt was a very productive company words that haven’t been said in at least 50 years
Thank you so much. You do a great service to the firearm and history communities. I would wager that your channel is the most BS-free firearm channel, not just on YT but in all of the internet on any platform. Thank you sir.
Would love to listen to SAS & The School of the American Rifle talk about AR's. Not sure who's got the most knowledge of an AR15, but they both can go deep into the system.....
You have to ask! 😂
Amazing video! Very glad that someone has finally addressed the upper receiver / cam interaction wear that has been bugging me on the piston AR's for about 8 years! I own a few PWS (primary weapon systems) long stroke piston guns and they all have it. PWS claims this as "normal wear" and will not address it.. Seeing as they copied a lot of colt's design, I am surprised that the metal plate in the upper receiver mod did not get carried into the PWS MK models as well.. cost savings of just using a mil-spec receiver I guess. You mentioned that this wear would cause problems so interested to hear about those if you could elaborate.
I put a POV roller cam pin in mine, so far so good.
It's great to hear straight forward information without ego being injected.Especially considering your vast knowledge on the platform as well as actual hands on experience from years of work and dedication. Thank you.
Thats funny. I just read an article by a former green beret on how the Ar15 wasnt a good prepper rifle. He refrenced that 2007 test. I called BS. Thanks for vindicating me. All my ar15s work great in sand,dirt,and mud. Like I commented in the article as ling as its not an old clapped out rifle they are gtg. I may be wrong but i think the DI system is better for dirty muddy conditions because it blows debris away from the ejection port.
I agree because if you look at the mud test from inrangetv it blows the mud away.
@@bobbyraejohnson yes. The piston system is good if your a tier 1 operAtor who lays down heavy suppressive fire on the regular. For my needs a DI is just fine.
Those tests had a flawed premise, as well. Most of those rifles were full auto. The M4 use a cam-based burst trigger. Meaning, the cam has to cycle three times before it will reset, so if the bolt locks back before it cycles all three times, it will only cycle the remaining 1 or 2 shots, then reset. Every time the M4 failed to fire all 3 rounds, it was counted as a malfunction. Paired with old, used magazines, and it's obviously nothing more than a shakedown.
Its mind blowing that Colt sat on the best technology and decided making a profit was *NOT* worth their effort. I always wondered why they didn't offer a piston upgrade to existing M4's in the mid 2000's since they had all the military contractors all they would have to do was offer cheaper upgrades to existing inventory and offer to produce the piston going forward and they could have kept Military contracts for another decade or more.
1:46 in all honesty that thing looks really friggin cool, like a USA made Daewoo K2
Well done at first I was not sure I wanted to listen ,then your knowledge blew me away !
A lot of great information there. I was able to follow along with half of what you presented here and you answered some questions in my mind, but I will admit the other half just blew me away and was over my head. I think I will watch this again and try to gain the knowledge that was over my head. What a great resource you are to these platforms. I wish you the best and will use a phrase that my Dad used when he was a live and he would say (you are a true gentleman and a scholar)
Thank you sir
That gas piston design, with the "thermal expander" also is there to reduce stresses on the bolt and lower receiver's bolt guides, due to the piston op rod hitting the bolt at an "off dead center angle" (the top of the bolt), which causes the forces of the action to want to force the front of the bolt up and the back down, as it slides back. Having the front of the piston able to flex, allows those stresses to dissipate before reaching the bolt, leading to a much more linear and gentle push rather than slap.
Why would a gas impingement system work any differently? The gas from the gas tube also hits the gas key “off dead center angle”, putting a similar torque on the bolt carrier, pulling up on the bolt head and pushing down the rear of the carrier.
@@5133937 Are mistaking a true gas impingement with a DI-Inernal Piston in an AR design? On a true DI yes, you're correct, the forces and the problem is the same, even on long stroke guns like an AK, but on Stoner's Internal Piston design, the gas is bled thru a tappet, which you might think is where the forces are applied, but there actually routed down behind the bolt, forcing the bolt and bolt carrier apart, which unlocks the system. Those forces being applied directly behind the bolt face, inline with the barrel, imparts far different stresses than slapping the top corner of the bolt carrier.
I should specify, "far different" and far more linear...
That Colt "M16A2" looks a hell a lot like a South Korean K2, externally and internally. Really, just the bolt assembly and recoil spring seem different.
Give customer what customer wants. That's the mantra of any business that wants to get more clients. The delay in delivering what customer wants costs money. Russians had even re-designed the AK-74 to feature picattini rails and the result is AK-12/15/19 for military sales. Civilians get that and even more crazy, a split-receiver with a left-side charging handle in AKV-521. But while Izhmash could be forgiven for lagging in this (post-breakup economic difficulties and national gun laws), Colt did it all to itself.
You've explained it as if Eugene Stoner would of!!! Thanxs!!! :-)
Love your videos, when are you gonna reupload the M4 history and development part 2?
Was just uploaded as we speak! -Heather Bartocci
imagine having this wealth of knowledge, and obvious critical thinking skills, and tech know-how, and the communication skills to explain these concepts, and then working for the Zap Braniggans up at Colt who just dont want to hear it.
Mega and Aero both use to sell true one piece monolithic rail/recievers. C.o.p. design i believe they called it.
JustAnother InternetExpert i have a Mega Maten with the MML handguard system. I think it’s better than a one piece. It’s just as rigid, but much easier to work on, should you ever need to. Mega’s one piece was called the Megalithic.
I just bought one on Gun Broker, arriving next week....
Love your videos. You're a wealth of knowledge
Would like to see the recoil canceling system from the AK retro fitted onto the AR.
Awesome Video ! Thank you !
Hi Chris,
Have you ever seen a Factory Colt AR (any model) that carries the name 'Commando' machine inscribed onto its Lower Receiver?
Thanks,
Bob.
Appreciate your in depth analysis of this weapon system.
MrRmh3481 I’m not Chris but you certainly can buy the Colt 6933 SBR which has “M4 Commando” on it’s lower receiver. It’s actually still in-stock at ArmsUnlimited.
Believe Very rarely they do exist from back in xm177 days too (70s)
Very information, and thank you.
Classic - I do like the look of the coyote type c. Man that would look great with a Glock 19x...👍🏻🇺🇸
Subscription earned good sir!
I wish colt would release this.
Big Bartocci has forgotten more about these rifles than I've learned about them, and I like to think I'm fairly knowledgeable on this shit.
I wonder if you can show how to do a barrel swap on the LE6940? Another question, The direct impingement model, can it be changed to a piston version with aftermarket parts? Or even Colt parts, if available??? I've got one that I use as a every day use rifle. I've changed out a lot of the Colt original parts and have them put away in case I ever need to sell it, but I wish I could change it to the piston version.
Your an amazing fella
I’d love to see you compare this firearm to the Taiwanese T91/Wolf A1
hmmmm my m4le 12" has been topped with a PWS Diablo gas piston system now for the past 15+ years and shows absolutely no wear like you mention at 29:45.
is it a possibility that by securing the piston rod to the bolt carrier eliminated the flex or jump?
Chris, are the 2007 Dust Test reports available for us to read online? Did they use MIL-C-71186 for the tests? Is there an anti-tilt pad on the bottom-rear of the bolt-carrier of the LE6940P? Is another reason for the articulating rod on the LE6940P to allow the operating rod to alleviate some downward force on the carrier and reduce carrier tilt? Thank you for making clear that the AR-15 is not DI (e.g. AG 42, MAS 44, LR-300, etc). I've struggled with nomenclature to describe it, but I like yours, "Internal Piston."
Recently, I discovered Superlative Arms sells an external piston kit that attaches to any AR. I wonder if there's more...
Very interesting. I end up wanting to hear your overall conclusion/opinion about these systems. It seems clear that you think criticisms of the so-call direct gas systems is overblown, but I'd like your final word: would our armed forces be better off if they switched to an external piston gun? If so, which gun or piston system do you think has the most promise? Big question, I know, but I get the feeling you would have an interesting answer.
Bendirval I think internal piston works just fine. We just need our military to properly maintain all the weapons in its inventory.
@SmallArmsSolutions My Colt LE6920 (2013) selector does not have the notch on the other side :/
Thank You for sharing some of your knowledge and telling us some little know history of this epic weapons system! Seems like Colt became a victim of their own arrogance.
Another Great video !! Well Done !!! I'll bet that most of Colts problem's were due to " Bean Counter Dogmatic Syndrome " !!!
I already commented on this video, but here’s two more questions… I have an LE6940 & I put Troy Industries Battle Rails on it, they’re just about the size of the Knights but available and probably half the price. What I’m wondering is if you think the Manta Low Profile or Wire Management rail covers, even Daniel Defense rail covers feel smaller, better in your hands than the Knights, Troy Industries rail covers??? Cuz I think the Troy feel big in my hand… I saw you had both types on your rifles.
Other question… I saw you had both Vltor and Rodgers Super Stock on your rifles, also. It’s hard to determine on video if either one is longer than the other. It appears that the Vltor is shorter.
I’d love to know if I could put a piston system into an LE6940
I remember colts articulating link piston
Chris, I have a Colt 6940P "Piston Carbine" complete lower. With the price and lack of availability of the 6940P upper on the secondary market, I have a question regarding the standard 6940 upper. Do you know if I would be able to purchase a stripped 6940 upper ($499 @ Brownells) and build it with a Superlative Arms piston kit? I'm mainly just curious if the OP rod would fit into the receiver. I assume it would but I've never seen a 6940 upper in person.
dubya 87 not sure, not familiar with that kit
@@SmallArmsSolutions yeah I'm kind of thinking that I should just wait to find the correct 6940p upper and just buy one complete. If one ever pops up for sale at a decent price
dubya 87 sorry to tell you, Colt has not and will not sell that upper. External piston guns are only for sale to Le and military.
I know. A few have popped up on the secondary market but its very rare and they aren't cheap when they do.
Yes, the SA kit WILL fit. Best piston kit in the world IMO. Far better than Adams Arms. VERY light weight. I LOVE mine.
This beard from the past is better
I agree. But he doesn't listen. - Heather Bartocci
Very interesting.
Why not use a roller cam pin like POF uses??
Hey Chris,
Seeing how Colt is more of an assembler now like BCM, do you feel their parts and QC are on par with BCM?
The handgaurd was too short on the 6940p just like Sig 516. No one wants a 7” rail.
Hence, it’s why both didn’t sell well
Caleb Clark I prefer the shorter rail. I don’t do that Costa sword hold
SmallArmsSolutions
I get it. But it just looks dumb. I love the fact Pws has full length rail. Lwrc also made theirs longer with the ic-a5. Both better piston rifles
To each their own. But I think adding more weight (via a longer rail) for no functional reason is dumb. Doing anything just for looks on a battle rifle is dumb to me. I’ll take the lower weight over looking cool any day. But hey, if you’re really into looking cool, I’m sure there’s an Airsoft gun out there for you.
Trey Gregory
Lol. You’re a major pussy if you can’t handle 3 more inches of aluminum handgaurd. Also, the 516 is far from a battle rifle. Lol
Trey Gregory a longer rail gives you more space to rest your gun on barriers to take shots without resting it directly on the barrel, avoiding a change in point of impact.
Did the modern LE6940P system eliminate the bolt tilt problem?
PotatoMasher had ramps on bottom rear of the carrier
Like the superlative arms carrier.
You talk a bit about the cam pin causing damage to the receiver, I've also heard this noted from others as well. I understand how the system works however I feel as though I am missing something. I am no expert so pardon my ignorance but why does the cam pin have the large head on it in the first place, especially if it runs the risk of causing damage to the receiver?
I would think that the square head keeps it from falling into the carrier, or maybe it's baring surface is more for alignment so it doesn't fetch up in movement. Not sure
Isn’t the 416 what the USMC uses? They call it the M27, but it’s the same weapon.
Slightly modified 416, correct
I wonder what a Colt LE6940P is worth now they stopped making it
In the end, the M4 wins.
what is the white thing he is holding on his chest?
I believe he broke his back at one point and this is a brace. It's an older video, from not long after he started his first channel (which was deleted).
A video from a year ago when he was in a brace. A tree broke his back. -Heather Bartocci
So, the AK uses a superior gas system?
I say this hesitantly because of the mention of an AR piston system needs to be overgassed...
I wonder what the difference is with the AK that makes its system different?
AK's are over gassed..
Why did this marine officer ask for the rifles in 7.62x39?
joe r was never given the reason, that was the requirement.
joe r potentially spec ops use. But I’m speculating out of my hindquarters
Grass is always greener...
@@GunFunZS At close range where most of actual assault rifle killing takes place (well-inside 200m) 7.62x39 is a very potent cartridge with a heap of "thump". With a 200m zero the bullet climb out of a 16.3-inch barrel is maximum 10cm inches at 100m, so it's pretty good for most real-life engagements. Even US military concedes that at 200m a 5.56mm M-16A2 has a hit probability of ~20% due to battle stress. Optics help, but there are other nuances.
Today most body armor will stop the old M43 7.62x39, but then it's a standard copper/lead bullet. If we were to make it in a same construction as Russian 7N10 or US M855A1 it'd have good penetration too.
At the time 7.62x39 was more impressive comparing.
It looks like a cetme rifle..
Did he say DIRECT IMPINGMENT?
Was young and ignorant!
I am def sharing this. About 0 people believe me when I tell them the AR-10/15 gas system is an internal long stroke piston...nor a delayed gas impingement system instead of direct impingement which means the gasses pushes directly against a flat surface .most piston systems use direct gas impingement to push the opp-rod/piston. Osprey defense pistons use a delay in the form of a gas expansion chamber type piston and gas cup on the opp-rod. It's my personal favorite short stroke conversion. Anyway Colt wouldn't call it an external piston just because. It would simply be called a piston system. The need to specify hints at the fact there is already a piston,and they are changing it's position from internal to external. Sorry to rant my brain goes Into overdrive when I listen to people who actually know what they are talking about.
The heck is bartocci wearing?
Beach&BoardFan u It is a back brace. Sometime in 2016 Chris fell off a latter or something and broke his back. Many videos on his old channel( prior to being banned) in 2017 have him wearing this back brace.
GuitaristOnTheRoof wtf did he get banned for?! If his old channel was anything like this, there’s nothing even remotely controversial!
All designs have advantages and disadvantages, however why is it generally accepted that pistons are inertly more reliable that DI?
It’s not
Only one in civilian hands you say? Can we get a 9-holes review?
Never been fired, never will while in my collection
@@SmallArmsSolutions Understandable. Would you ever allow someone with extremely precise measurement instruments to measure it down to the finest detail so others could replicate it and fire a copy?
@@JohnDobak I would never allow it to be disassembled beyond field stripping
Algorithm.
Specifically, what is an external Piston external to? And, what is an internal piston internal to? They’re nonsensical terms. Prove me wrong. It’s as bad as, “My pronouns are…”
What is opposite of direct impingement? I’d say indirect impingement. But I’m a conservative.
You get Chris Sirois on and laude him for his achievements to include the Sig 516 and in other VDOs you claim the Colt M4A1 is top dog. It begs the question, “Why isn’t Sirois designing Di rifles?
Because he refuses to believe contaminating lower receivers and BCGs with debris is an ingenious design strategy.
Internal to the BCG makes it external to the gas block. If you’re going to double talk and manufacture obfuscatory nomenclatures, go help Greta Thunberg with climate change.
I love ya Bartocci but clean it up.
Dude, you lack any form of mechanical understanding. The M16 is not direct gas impingement. You can look it up! It is a piston made up between the bolt and carrier, hence internal piston. External piston means the piston is locates outside the receiver and on the gas block. If you lack that understanding, nobody will help you. Im curious as to what your experience is? I doubt you have worked in this industry and watch to many RUclips experts who have never worked in the industry. Also, the military never referred to the M16 and direct impingement. Some uneducated moron just came up with a wrong reference name and it stuck.
@@SmallArmsSolutions • Gas-operated (Expansion of gas within piston inside bolt carrier), closed rotating bolt.
Alright Mr. Bartocci, tell me you didn’t add this to Wikipedia. Nobody else is anal retentive enough to do it but you. Tim from MAC but he’s not that familiar with sophisticated nomenclature.
You already conceded its generic operation is termed Di, for good reason I might add so, I will stipulate it is indeed a Gas-operated (Expansion of gas within piston inside bolt carrier), closed rotating bolt. Give me a break Chris, I’m retired from a major airline. I started on fighter jets in 1978 at McClellan AFB. I’m a licensed aircraft mechanic since 1983, though, licensed too is a generic term. It’s more correct to say I hold a DOT Mechanic’s Certificate with ratings of Airframe and Powerplant. That’s a mouthful. That’s why Di and piston are used and not bombastic language and to some, as in your case, obfuscatory meanings. I say that without reservation or compunction because direct impingement is a type of gas operation for a firearm that utilizes gas from a fired cartridge to impart force on the bolt carrier or slide assembly to cycle the action.
You always say, “I know some will disagree with me - put it in the comments.” You’re a great teacher Chris and a great man. We just don’t agree. No disrespect directed to impinge upon your persona.
Stating facts is not being anal, it’s being a professional. One who has worked in this industry. You are good spreading misinformation, good for you. Direct gas makes no use of a mechanical piston. MAC is professional, he spreads proper information. Im not here to convince a closed minded individual who ignores facts. If you dont like my approach to my profession, there are many hobbies run channels you can watch.
@@SmallArmsSolutions • You ignore the fact I went on record and stated you were a great teacher and instead focus on my contentions.
If calling it an internal piston gets it for you and Tim, then rock it. I watch all of Tim uploads as well as yours. You are both quintessential professionals. That doesn’t mean I agree with every jot and tittle. It does mean you don’t start every VDO with a sophomoric vaudevillian skit.
Professionals use both operating systems • that doesn't mean one isn't superior. If one system can adjust for climatic conditions, a variety of ammunition, and suppressor use, it's a no-brainer. Di supporters are analogous to climate change activists; they believe in something manufactured that only exists for those in the swamp that can profit. You’re brainwashed like a liberal. If you can’t wrap your head around the 3 reasons I just stated, you’re loyal to a tainted cause. Why isn’t Sirois designing über internal pistons? Di’s are so janked they’re manufacturing adjustable gas key/gas paths. I can only laugh and applaud your devotion to Mr. Stoner. Adjustable gas paths are inane when compared to an adjustable gas valve. Chancing polluting the lower receiver is inane. Which one of us is disseminating misinformation?
This is where you shine because you have inside knowledge. I don’t know if the following are true but I would trust YOUR information.
The SIG MCX rifle has been used by various militaries and SWAT teams, including the Ukrainian Armed Forces and the U.S. Special Operations Command. The MCX-SPEAR/XM7 has also become the new standard issue rifle for American soldiers. The British police and SAS troops also use an older version of the SIG MCX called the Virtus.
I don’t expect a reply, I cut deeply on this response; didn’t leave you any wiggle room. If Sirois won’t tell you, I will.
You have obviously no experience with internal piston rifles, at least none in the real world. You dont understand the mechanics and not even the history. Chris Sirois is a friend and colleague and we have worked together on a few designs. Im also guessing you’re not a veteran who has used these systems. Each has it areas where they shine. Your misguided opinion is based on commercial rifles build to no military standards. If you understood when tests these guns go through and pass you would not make such misguided statements. I am very familiar with what the Ukrainian Army uses, I have worked over there 3 times. You? I have spent a significant ammount of time at Fort Benning and Bragg with SOF. Have you? M4A1 has been most of their weapons of choices. I have also took part in weapon replacement programs all over the world. My guess is you have not. You have not see these different platforms compete head to head. The external pistons shine in short barrels, short barrels suppressed, over the beach and bore obstructions. The US Army has been very pleased with the performance of the M4 which is why it’s still in use. None of these other weapon have offered anything significantly better. Most of the people who speak as you, are people who are tinkerers, buy substandard components and often done know how they go together. Sometimes you need to keep your ears open and mouth shut and listen to those with experience. I fully state in several videos where certain weapon exceed some of the parameters of the internal piston. Those generally are limited SOF situations. Chris Sirois and many other engineers will tell you the same. Chris has not messed with internal piston because he was asked to build external piston guns. For military contracts, there is not really anyway to compete with Colt, LMT and for some small part KAC. Chris exploited the strengths of external piston and went in that direction. Same as many other companies making external piston versions of the M4 (HK, Caracal, Beretta, LMT….). Military weapons are not meant to and should not have adjustable gas systems. Suppressed and unsuppressed if the system is not balanced for both. Internal pistons do not require it in military weapons with military ammunition. If you understood engineering and Military-Spec, you would understand that the weapon is designed around a specific round with a specific propellant which has spaced out chamber and port pressures. You dont need adjustable gas for this. In the commercial arena where you have ammo all over the spectrum, there it becomes a balancing issue. I dont expect a response. This is a. Sharp dose off reality of this industry and the mechanics and how weapons are designed. Which isn’t clear you have no understanding of. I try to educate people on the right points. But there are some people out there, you cant teach them a thing. They are so caught up in their own head that you could show it right to them and they would disagree.
1stist
Greetings…off topic info request. I recently purchased a 6940P. Any suggestions on obtaining an operator manual? Thanks for any help you can offer.
Steve
I wrote manual for the LE 1020. I never saw one for the LE 6940P. Does not mean there was not one.
@@SmallArmsSolutions
Thank you