Most people refuse to understand this. I've even worked with mechanical engineers who doesnt believe in GDT for particular products. When I did an internship with a gun parts manufacturer, this was very very very important. That's the edge of a completed firearm off a great QA/QC'd manufacturer. Not only are the individual parts qualified but the completed unit is system qualified. Of course not every firearm manufacturer who claims to do so does so. That said I still do enjoy building from parts and testing.
When I was a machinist, I got an engineer fired for his tolerance stacking issues. He designed an assembly for our semiconductor handling machine. It failed to work. I came to him with a stack of blueprints and told him he had a couple of ways to correct the issues, and he threw a fit. Then he tried to fight me. Then he got fired and I fixed his blueprints. Tolerance stacking is going to happen not matter what, otherwise the parts would be so costly nobody could afford them.
I work with an experienced engineer with almost 30 years experience. He’s one of the most intelligent people I’ve ever met. Very seldom do you meet a person like him that’s book smart and truly mechanically inclined. He has no ego doesn’t care who’s right or wrong he just wants things to be right. My first week under him he taught me about this certain issue.
I am a mechanical engineer. I work more in the architectural side now but worked in ASME pressure vessel certification for quite a while. We have to educate architects all the time that if each of your wall dimensions on your building are off by 1/8th of an inch then by the time you get 40 walls in you have grown or shrunk the building by inches. We call it error propagation....but tolerance stacking is just as good. Where we run into it is that drafting programs can be set to round off a dimension to the nearest fraction...1/8th, 1/16th, 1/4. Whatever.....you can round to the nearest inch or foot if you want. Rounding to the nearest inch in a site plan that is 200 acres is not a big problem......rounding to the nearest inch in a formed pressure vessel head is a big problem. Many buildings as you see in urban areas are built right up to the property line. So being out 6 inches in 100 ft can put you building onto some else's property. In small part machine design (like guns) it's better to run in decimal inches and have your CAD program set to something smaller than comparative runout on your machinery. If your milling machine is accurate to a ten thousandth....then set your program to round to the nearest ten thousandth......or as accurate as your measuring capabilities. We have had associates that worked building nuclear vessels in different countries. They actually have to design measurement tools in the US to be used in Sweden building a nuclear vessel.....then have it all fit when assembled in Korea. So they take the environmental and temperature considerations into the design so that everything fits in the weather if it's destination.....down to the thousandth...... So....some engineers know....and some don't. It usually just experience or lack of.
And that is why we have Gunsmiths like you who went to school and learned a trade, then you have Gun hackers need U explain. Very good video. Thank you for sharing with us.
my first generation daniel defense M4 has the exact same problem. it feeds fine when the gun is clean, but every single bullet is scratched to hell when they get chambered, and i mean a line of really DEEP scratch, which results in less than stellar accuracy. i was shocked to see such elementary problem could ever be found in such a reputable company daniel defense. but since reliability doesn't seem to be affected, and i have many other ARs to shoot, i never bothered to send the gun back to DD for repair, kind of just put up with reduced accuracy for the past 10 years, and i still have this gun in my collection.
I have similar issue now. For some reason it’s ALWAYS the first round that gets stuck, half way up ramp. If I re-rack the Bcg and let it spring forward a 2nd time it then will finish up the ramp. So it’s not perma stuck, but still a bad bite. And what’s even more weird is every round after that cycles 100% fine from standard gas pressure cycle. Will prob just sand it down myself I suppose
@@carsonhunt4642That almost sounds like you're loading your magazines to 31, which can cause that exact problem. I don't know how you would have that consistent problem always on the first round otherwise. I could be wrong, though
So do you use any kind of jig or fixture to grind feed ramps? How do you ensure that you're not changing the angle? I'd love to see a video about this...
I'd like to thank you for all the information you provide through your videos. Especially the tips on what to check without fancy gauges or tools. Followed all your tips and have my first AR15 build functioning flawlessly. Your content is much appreciated.
When I built my 300blk last year, I had the same problem. Luckily I checked it prior to installing the barrel nut. Grabbed another stripped upper from the bin and worked just fine. Good video!!
@@SchooloftheAmericanRifle Sorry if that is what I seemed to imply. I've just always heard Maryland gun laws are some of the strictest in the country and was looking for some background I guess. Just being lazy and not wanting to do my own research. And while I've got your attention, just found your channel and wish I found it long ago. Thanks and keep up the great and informative videos
Thank you for doing this video, some people believe that just because you buy all “Gucci” parts that you Just simply can’t have a problem, well obviously you can 🤷🏻♂️ (love all those manufacturers btw👍🏻👊🏻)
Ha I was going to ask about this issue on the fb page lol. I have a little bit of the same with a rasco barrel and umbrella corp upper. Its ever so slight but im holding off until I have the rest of the components for the build. Now if I could only locate a umbrella bcg and my umbrella corp complete build would be complete! ..... thanks again for the awesome info Chad!
I recently RE-built a lr308. I put a FAXON 20" big gunner bbl on and a Larue mbt-2. The lr308 upper has no feed ramps and the bbl extension seemed a lil rough. The upper basically had a "lip" over the bbl ramps. So i and a friend came up with a tool to smooth it. Mind now i had no issues at all after bbl break in and subsequent shooting. 150 rnds or so. But because there were rough spots i smoothed it out. We came up with a dowel wrapped w a 600grit paper and i lightly dragged it down the bbl extension ramps. Only until the rough spots couldnt be felt and the lips extending over bbl were much smoother... shoots great with 165g hornady projectiles...
HAD (emphasis on had) a centurion proper mk12 mod1. had grouping issues during break in and the first 400 rds or so. sent it back, they said i mag dumped and had about 1500-2000 rounds through it, and sent it right back to me. then i showed them proof of the ammo i shot and they took it back immediately. sent me a new barrel and after all this hassle youd figure theyd qc the barrel... nope. breech face of the barrel had chatter marks from the reamer . Sent it back and got a full refund. Decent people there, but wouldnt buy barrels from them periodt. great vid btw always learn so much
Another example I had is when I combined a G trigger with a Balios Lite lower. G pins are a little fatter than Milspec and balios trigger pin holes are a little tighter. I got the trigger installed using g pins, grease and more hammer than I wanted to.
There is a lot to be said for purchasing a completed upper from a single source. They have identified any stack up issues with their suppliers and have resolved those issues. Left on your own, its up to you to see what you get. The most important aspect is that you are left to retrofit the components on your own or try different parts.
Hopefully they have IDd stacking issues and resolved them. Hopefully. But ultimately, no matter who is the seller of a complete upper, it's a QA/QC issue -- and not every seller of complete uppers has airtight quality controls.
Great video and content. Is is possible to utilize barrel shims to bring the two surfaces of the feed ramp more level versus lightly removing material from the barrel feed ramps?
Great video. Thank you for that knowledge. Potentially stupid question. In this scenario if the overhanging distance of the feed ramps is extremely small would it not be possible to "shim" the barrel where it meets the receiver assuming your "shims" are properly coated to avoid electrolysis? I am no kind of expert by any means. Just know enough to get myself in trouble 😁
Thanks for the video. I can’t find the answer and I’m waiting to hear from Springfield Armory but I bought a saint victor 5.56 and I noticed dents on all the star corners “extension lug peening” and my feed ramps aren’t aligned, the feed ramp goes more right. My bolt looks okay but in your video when you shined the light I have dents on all the star cuts there…I just bought this and fired only 100 rounds and pre cleaned it before hand. Ive used AR”s in the service so I know an okay amount. they recieved the returned firearm last Thursday and I waiting to see if they exchange or repair it.
Do you happent to know an approximate round count through this upper and/or would you consider the wear on the catch for the charging hangle to be normal? It looks a little excessive from here.
Pardon a 'Newbie' question but, would using Barrel Shims (between the barrel and the barrel nut) help correct the problem of that feed ramp snag you demonstrated with the q tip end? and, what would you recommend for polishing/reducing that overhang? I have quite a few spare parts i would like to experiment with to hone my hobby. Thank you for the informative videos.
I've seen a lot of barrel extension issues with a few of the nicer uppers. I have personally repaired this issue on an upper I have. After polishing and cutting the ramps shorter by .012" then polishing to a mirror finish my feeding issues ceased.
In other words parts may be made to spec, but if one part is say, at the low end of a tolerance and the other parts are at a high end of a tolerance....shit doesn't always work. Check out subjects on Geometric Dimensioning and Tolerances (gd&t) if you want to learn more! Great video thanks for sharing!
Is there a print they machine to and what are the tolerances? I'm amazed in the cnc era there would be a visible lip. That looks to be over 100 microns! Maybe they left extra expecting you to do a bit on hand finishing? Looks like a touch or two with a stone and a bit of polishing it should be good to go. Suppose I'm spoiled because I work in a temp controlled shop... still even in an old sweatshop I wouldn't expect a lip there. QC must have been drinking lunch that day.
I'm thinking if I built that, I would have shimmed the barrel so that it was shy of flush to the M4 notches. Or, took the airtool and polished them flush. I am a Blackout enthusiast, and you gotta fatten those babies up a little. I did mine, and test chambered a 85gr penetrator round without a hitch. It's really short. 220's feed well too. But the pathway has to match it's function and smoothly.
My first ar had feeding issues i found the barrel extension had burrs on the feed ramps that were the issue a rat tale file and a dremel buffing wheel fixed it but now I know to check for that before accquiring another.
Trying to find out why my new Stag Arms Stag-15 AR is not feeding the rounds when I try to load the first round. Rather slingshot or bolt catch ... The round gets stuck on the the ramps and the bolt stops halfway trying to chamber my first round. I half to recharge the handle and it works after that (pushing the round the rest of the way). I thought it was cause my spring or buffer was no good. None of my other AR pistols do that tho. However my other AR'S are 7.62. I think this is my problem here. Also I think my PMAG doesn't present the round high enough like my 7.62 DURAMAG.
Absurb paying all that money for a high end part and the company cant even do the job correct. Its rare nowadays to find a company or even a person who takes enough pride in their work to do things right. Instead they just take the money and put out poor parts with terrible QC. Pay a premium only to have to pay a gunsmith to do it properly. Makes me question buying from criterion now.
That’s interesting. I understand that individually, each of those companies make quality parts. When we talk about specs & tolerances, I’m not sure where they are derived from. Assuming the tdp? With that said, I don’t think that barrel or upper are used in government weapons. That aside, it’s entirely possible / plausible for every part to be in spec, yet the weapon not function properly? Is that why usgi manufacturers have government inspectors randomly test completed firearms?
What is your going rate for doing something like that and how do we make arrangements to send you something? I used a different upper when I encountered this (also all quality components), but wonder if I should just have this process done.
I have an issue with my PSA 10.5” upper. It chambers fine but when you go to cycle it manually or fire it, it locks up and won’t eject the round and it needs to be mortared to get the bolt free. What’s my issue?
I have a Ballistic Advantage barrel on a Geissele reciver and it has a slight step like as shown on this video but it’s feeding correctly and I have no issues with it up to now. It probably has 200 rounds through it at this moment. Would this be something to worry about? Could it be a issue later? Should I change the barrel out?
good video sir, you are a wealth of info, thank you. i have found that comparing a FN to a BCM to a PSA, the BCM upper always wins hands down in the QC fit and finish and indeed in the feed ramp area as well. the 3 uppers i mentioned, the bcm one has the best looking m4 feed ramps, they look like they were either polished or machined so they had the appearance of a mirror right from the factory.
Kinda puts a damper on wanting to make work area, buy ALLL the tools, all the major and minor part groups and all the high end, custom, hand selected components and pieces for the perfect build only consisting of the best of the best brands from the stock down to the smallest roll pin tip to butt, top to bottom. Just might not be worth the time and expense after all. $$$$ and still have problems 🤔
What if the problem is reversed? And the barrel extension ramps are just shy of the receiver ramps? As if too short. The extention index pin is fully seated in the notch and barrel nut is torqued to spec. I have this abnormality with 3 uppers. All bcm assembled upper receivers and 3 different barrels. A Centurion, a bcm and a Daniel Defense. Seems like a bcm problem to me. Any issues that anyone can forsee?
I had a feed problem in a ruger. It wasnt the gun. It was the mag holding casing too long causing a jam. I switched to magpal clips and no more problems.
Yea so I thought for sure this was my problem but I put the wrong bullets in didn’t even know 300 aac blackout was a caliber I thought it was a all black ar
have the same problem with a PSA upper I just bought for a build, Geez the one shown on the video is awesome compared to mine!! I put a mag full of ammo in and tested it before I would actuallt shoot it, you name it it did it, FTF, FTE, DOUBLE STACKING, It takes the cartridge right into the barrel upper, the ammo had gouges and one bullet actually went back into the cartridge which put gunpowder everyehere!! gonna have to send it back, from what i've heard thats gonna be a delightful event ! I'm sorry to all the PSA folks out there but this is not a good quality rifle or componets, i've always been leary about PSA but I finally drank the Kool Aid and very sorry for doing so. I have a Bear Creek Arsenal upper that is 10+ better then this PSA upper, better quality all the way around, the charging handle is..well lets just say my wife have better quality cooking utensils, I hope this is not gonna be a big drawn out procedure but probably will, not to mention I destroyed about $15 worh of ammo... well the bright side is I dint just go out and shoot it, I may have gotten Injured or worse
As the video said you'll potentially these problems regardless For instance i know people who have PSAs thst are perfect As seen here a high quality part has a serious issue If you aren't even going to listen or think why comment on this shit? The reality is it doesnt matter if it cheap or expensive big brand or not all of them are prone to fuck ups instead of going "yep got the most expensive part on the market" take the time to actually check your part and realise it can be a fuck up nomatter how much you spent
Why would an issue like this not get picked up in quality control inspections at the manufacturer? Clearly, I am missing something in how these things are built.
One would not wish to remove the finish from the softer receiver metal and expose the aluminum to the steel risking cross contamination resulting in corrosion.
@@TEXwithNODS Three fold: 1, the receiver feeding guide grooves are already larger than the barrel feed grooves and therefore do not require the removal of material. 2, removal of the finish from the aluminum coming into contact with steel will cause the aluminum to corrode by means of electrolysis. 3. Since the barrel simply slides in and out of the receiver when the barrel nut is removed there is no need to while contouring and test fitting the barrel feed ramps to said receiver.
Why not just add a shim between the barrel and the upper? If you could properly gauge the offset problem on the ramps, they could possibly line up correctly without physical grinding.
Pushing the barrel forward can allow the carrier to travel further forward. If this happens the buffer retainer can impact the buffer slightly or with force. Not good.
Thanks for the reply! I guess I should have started off with one would also have to measure the internal dimensions of the barrel extension to see where the extra growth is. To your point.. if the breach face of the extension tolerance is too rearward, this would cause excessive wear on the bolt face. The tolerance that is the root cause should be identified to better know what has to move. I absolutely love gun Nerding. 😀 keep up the great work. Excellent Channel!
Has anyone ever heard of Pro2A tactical. I was looking at getting a 7.62x39 at setup and they are about the only place I am able to find with uppers available. Any help would be appreciated. Thanks. And as always. Thanks for another great informative video to help us all out
I'm curious why that caliber would be your choice? Nothing wrong with it of course, but it seems like if you are going to go with an "off" caliber AR there are much better choices on the market these days, like 6.8SPC, 6mm-ARC, .300BLK, or my favorite 6.5-Grendel. The 6.8 gives better ballistic performance than the 7.62, and if you're shooting past 300-400 yards the Grendel is a monster out of the AR platform. This day and age you can get most any of them for reasonable prices (when stores had ammo anyway) and with their popularity if you realod brass there's literally hundreds of combinations you can make to really fine-tune your preferred load.
@@TheFishE77Official I’m looking at 7.62 x39 because I already have other calibers and at the moment 7.62x39 is the only ammo still available. I don’t want to shoot it all my 5.56 and 9mm and I’d still like to be able to shoot on the weekends. I can get 1000 rnds of steel case for about 350 so I can shoot and not worry about burning up expensive and dam near impossible to find ammo. This rifle also isn’t for hunting or defense it’s just to target shoot and have some fun I’ll be inside of 150 yards at pretty much all times. Even I did hunt with it where I hunt I don’t get shots much past about 50 yds on average.
@@icantsaywhat Fair enough, and hey you can never have enough guns! Give a look around sites like Gunbroker if you're needing to feed some of your others, plenty of ammo to be had for all calibers. I just picked up a case of 250 rounds of Hornady 123-grain ELD Match 6.5Grendel for not much more than regular retail. I've been finding Wolf Steelcase Grendel ammo super cheap too, and in stock pretty much everywhere. I'm sure you could grab a deal on 7.62 there.
I had Core 15 rifle from a few years ago that had this issue as well as multiple others. Easily one of the worst rifles I've bought and I'm thinking due to the Sandy Hook scare. The feed ramps on the barrel extension severely overhanged the m4 feed ramps of the upper, the wall thickness of the lower receiver was thicker on one side, and the rifle was heavily overgassed, it ejected shells at the 1230 o'clock position with shells marring the handguard immediately in from of the ejection port, recoil felt like a light 20 Guage shotgun.
I have a question, but in reviewing the comments (in order not to be redundant) which have been made over the past 2 years, I see that you don't answer questions. That's unfortunate.
One of the reasons I prefer non-feed ramp upper receivers when building an upper. I use a Dremel with a Cratex bullet shaped bit and polish the ramps on on the barrel which also causes the lower to polish in perfectly matching ramps.
One of the reasons he is pulling the barrel to do the feedramp work is that he doesn't want to cut into the anodizing. The bare aluminum is much softer than the anodizing. Was glad he mentioned it because ive noticed the same and stopped removing the anodizing on any bearing surfaces when doing Cerakote. It leaves a stronger surface. Probably not a huge problem but with heavy use bare aluminum feedramp on the lower will land you with this snagging overhang.
You don't want to cut out into the uppers hard coat anodizing.. Cartridges will ding it up more and cause the same hang up issues like Josh said. Better to just remove the barrel to polish and match the barrel extension ramps to fit the upper m4 ramps. Sotar shows a video of this with a sons of liberty upper
Have you ever done an examination on any LWRC rifles? I have a LWRCI-DI 556 AR-15 and it has a unique type of bolt. There is no separate gas key; it is somewhat integrated into the bolt body with only a additional tube that is roll pinned into the carrier. Was curious how this would compare to other manufacturers.
Chad, Looks to me as if the upper ramps are lower that the M4 extension ramps, which to me would be the "worst case" scenario. Please do a video on how you fix this. I am extremely interested.
Most people refuse to understand this. I've even worked with mechanical engineers who doesnt believe in GDT for particular products. When I did an internship with a gun parts manufacturer, this was very very very important.
That's the edge of a completed firearm off a great QA/QC'd manufacturer. Not only are the individual parts qualified but the completed unit is system qualified. Of course not every firearm manufacturer who claims to do so does so.
That said I still do enjoy building from parts and testing.
When I was a machinist, I got an engineer fired for his tolerance stacking issues. He designed an assembly for our semiconductor handling machine. It failed to work. I came to him with a stack of blueprints and told him he had a couple of ways to correct the issues, and he threw a fit. Then he tried to fight me. Then he got fired and I fixed his blueprints.
Tolerance stacking is going to happen not matter what, otherwise the parts would be so costly nobody could afford them.
I work with an experienced engineer with almost 30 years experience. He’s one of the most intelligent people I’ve ever met. Very seldom do you meet a person like him that’s book smart and truly mechanically inclined. He has no ego doesn’t care who’s right or wrong he just wants things to be right. My first week under him he taught me about this certain issue.
I am a mechanical engineer. I work more in the architectural side now but worked in ASME pressure vessel certification for quite a while. We have to educate architects all the time that if each of your wall dimensions on your building are off by 1/8th of an inch then by the time you get 40 walls in you have grown or shrunk the building by inches. We call it error propagation....but tolerance stacking is just as good. Where we run into it is that drafting programs can be set to round off a dimension to the nearest fraction...1/8th, 1/16th, 1/4. Whatever.....you can round to the nearest inch or foot if you want. Rounding to the nearest inch in a site plan that is 200 acres is not a big problem......rounding to the nearest inch in a formed pressure vessel head is a big problem.
Many buildings as you see in urban areas are built right up to the property line. So being out 6 inches in 100 ft can put you building onto some else's property.
In small part machine design (like guns) it's better to run in decimal inches and have your CAD program set to something smaller than comparative runout on your machinery. If your milling machine is accurate to a ten thousandth....then set your program to round to the nearest ten thousandth......or as accurate as your measuring capabilities.
We have had associates that worked building nuclear vessels in different countries. They actually have to design measurement tools in the US to be used in Sweden building a nuclear vessel.....then have it all fit when assembled in Korea. So they take the environmental and temperature considerations into the design so that everything fits in the weather if it's destination.....down to the thousandth......
So....some engineers know....and some don't. It usually just experience or lack of.
And that is why we have Gunsmiths like you who went to school and learned a trade, then you have Gun hackers need U explain. Very good video. Thank you for sharing with us.
my first generation daniel defense M4 has the exact same problem. it feeds fine when the gun is clean, but every single bullet is scratched to hell when they get chambered, and i mean a line of really DEEP scratch, which results in less than stellar accuracy. i was shocked to see such elementary problem could ever be found in such a reputable company daniel defense. but since reliability doesn't seem to be affected, and i have many other ARs to shoot, i never bothered to send the gun back to DD for repair, kind of just put up with reduced accuracy for the past 10 years, and i still have this gun in my collection.
I had a very similar issue with a Barrett rec7. sent it in, they sent it back 'fixed', wasn't fixed.
I have similar issue now. For some reason it’s ALWAYS the first round that gets stuck, half way up ramp. If I re-rack the Bcg and let it spring forward a 2nd time it then will finish up the ramp. So it’s not perma stuck, but still a bad bite.
And what’s even more weird is every round after that cycles 100% fine from standard gas pressure cycle. Will prob just sand it down myself I suppose
@@carsonhunt4642That almost sounds like you're loading your magazines to 31, which can cause that exact problem. I don't know how you would have that consistent problem always on the first round otherwise. I could be wrong, though
So do you use any kind of jig or fixture to grind feed ramps? How do you ensure that you're not changing the angle? I'd love to see a video about this...
I'd like to thank you for all the information you provide through your videos. Especially the tips on what to check without fancy gauges or tools. Followed all your tips and have my first AR15 build functioning flawlessly. Your content is much appreciated.
You should make a video on how you fix this barrel
Yes this will be good after the apology video. Get right back at it.Don't worry what other say.
Probably just use a file to even things out
When I built my 300blk last year, I had the same problem. Luckily I checked it prior to installing the barrel nut. Grabbed another stripped upper from the bin and worked just fine. Good video!!
Hope to get to Maryland one day to take a Class. You cover things most do not. You are appreciated.
I fled from Maryland be careful what you wish for...
I didn't think these weapons were legal in Maryland?
Not all things AR are banned in Maryland. Everything I do is above board. I'm a FFL and wouldn't even think about violating the Law.
@@SchooloftheAmericanRifle Sorry if that is what I seemed to imply. I've just always heard Maryland gun laws are some of the strictest in the country and was looking for some background I guess. Just being lazy and not wanting to do my own research. And while I've got your attention, just found your channel and wish I found it long ago. Thanks and keep up the great and informative videos
Another great video of something to look for when issues come up. Thanks
Great reminder to always check components, no matter the quality or reputation behind them
Your videos are gold man, ty.
Another great video full of good information👍
I always blend then polish those two lower feed ramps after I’ve torqued the barrel onto the upper receiver
Very awesome information 👍 that’s something I’ve never even thought of.
Thank you for doing this video, some people believe that just because you buy all “Gucci” parts that you Just simply can’t have a problem, well obviously you can 🤷🏻♂️ (love all those manufacturers btw👍🏻👊🏻)
I had an Armalite factory upper that had the same issue. Armalite took care of the issue immediately and it was a fantastic rifle.
Ha I was going to ask about this issue on the fb page lol. I have a little bit of the same with a rasco barrel and umbrella corp upper. Its ever so slight but im holding off until I have the rest of the components for the build. Now if I could only locate a umbrella bcg and my umbrella corp complete build would be complete! ..... thanks again for the awesome info Chad!
Why I always cleanup my feed ramps.
New knowledge in my toolbox. Thank you sir.
Heck yeah another SOTAR video!
But we wanna see morreee!!! Damn I love this channel!!
I recently RE-built a lr308. I put a FAXON 20" big gunner bbl on and a Larue mbt-2. The lr308 upper has no feed ramps and the bbl extension seemed a lil rough. The upper basically had a "lip" over the bbl ramps. So i and a friend came up with a tool to smooth it. Mind now i had no issues at all after bbl break in and subsequent shooting. 150 rnds or so. But because there were rough spots i smoothed it out. We came up with a dowel wrapped w a 600grit paper and i lightly dragged it down the bbl extension ramps. Only until the rough spots couldnt be felt and the lips extending over bbl were much smoother... shoots great with 165g hornady projectiles...
Thanks for teaching us!
Thank you for sharing!
Solid info, thank you sir.
Thanks for the video. Luckily my Aero M4E1 upper and Larue Stealth Barrel w M4 feed ramp matches perfectly.
HAD (emphasis on had) a centurion proper mk12 mod1. had grouping issues during break in and the first 400 rds or so. sent it back, they said i mag dumped and had about 1500-2000 rounds through it, and sent it right back to me. then i showed them proof of the ammo i shot and they took it back immediately. sent me a new barrel and after all this hassle youd figure theyd qc the barrel... nope. breech face of the barrel had chatter marks from the reamer . Sent it back and got a full refund. Decent people there, but wouldnt buy barrels from them periodt. great vid btw always learn so much
Another example I had is when I combined a G trigger with a Balios Lite lower. G pins are a little fatter than Milspec and balios trigger pin holes are a little tighter. I got the trigger installed using g pins, grease and more hammer than I wanted to.
There is a lot to be said for purchasing a completed upper from a single source. They have identified any stack up issues with their suppliers and have resolved those issues. Left on your own, its up to you to see what you get. The most important aspect is that you are left to retrofit the components on your own or try different parts.
Hopefully they have IDd stacking issues and resolved them. Hopefully. But ultimately, no matter who is the seller of a complete upper, it's a QA/QC issue -- and not every seller of complete uppers has airtight quality controls.
Great video and content. Is is possible to utilize barrel shims to bring the two surfaces of the feed ramp more level versus lightly removing material from the barrel feed ramps?
Damn I’ve been out of it too long, didn’t realize FCD did handguards or uppers.
Love their stuff.
Handguard custom made for them by cmt. Amazing lockup, haven't tried fcd branded version
Great video. Thank you for that knowledge. Potentially stupid question. In this scenario if the overhanging distance of the feed ramps is extremely small would it not be possible to "shim" the barrel where it meets the receiver assuming your "shims" are properly coated to avoid electrolysis? I am no kind of expert by any means. Just know enough to get myself in trouble 😁
Great info
This is great.
Thanks for the video. I can’t find the answer and I’m waiting to hear from Springfield Armory but I bought a saint victor 5.56 and I noticed dents on all the star corners “extension lug peening” and my feed ramps aren’t aligned, the feed ramp goes more right. My bolt looks okay but in your video when you shined the light I have dents on all the star cuts there…I just bought this and fired only 100 rounds and pre cleaned it before hand. Ive used AR”s in the service so I know an okay amount. they recieved the returned firearm last Thursday and I waiting to see if they exchange or repair it.
Do you happent to know an approximate round count through this upper and/or would you consider the wear on the catch for the charging hangle to be normal? It looks a little excessive from here.
I've missed your videos. Thank you.
I have this exact issue with my FCD upper and Triarc barrel. Now to figure out where to send my barrel to get the ramps polished 🤷🏾♂️
Pardon a 'Newbie' question but, would using Barrel Shims (between the barrel and the barrel nut) help correct the problem of that feed ramp snag you demonstrated with the q tip end? and, what would you recommend for polishing/reducing that overhang? I have quite a few spare parts i would like to experiment with to hone my hobby.
Thank you for the informative videos.
My ACS mags would grab and hold on tight with those feed ramps.
Cool. Thanks!
You da man, thanks
I've seen a lot of barrel extension issues with a few of the nicer uppers. I have personally repaired this issue on an upper I have. After polishing and cutting the ramps shorter by .012" then polishing to a mirror finish my feeding issues ceased.
In other words parts may be made to spec, but if one part is say, at the low end of a tolerance and the other parts are at a high end of a tolerance....shit doesn't always work.
Check out subjects on Geometric Dimensioning and Tolerances (gd&t) if you want to learn more! Great video thanks for sharing!
Correct. I often oversimplify stuff for the audience and the more experienced people get frustrated with how I explain or don't explain things.
@@SchooloftheAmericanRifle nope I thought you did a great job, i was just giving a different perspective.....I enjoyed the content!
Is there a print they machine to and what are the tolerances? I'm amazed in the cnc era there would be a visible lip. That looks to be over 100 microns! Maybe they left extra expecting you to do a bit on hand finishing? Looks like a touch or two with a stone and a bit of polishing it should be good to go. Suppose I'm spoiled because I work in a temp controlled shop... still even in an old sweatshop I wouldn't expect a lip there. QC must have been drinking lunch that day.
I'm thinking if I built that, I would have shimmed the barrel so that it was shy of flush to the M4 notches. Or, took the airtool and polished them flush. I am a Blackout enthusiast, and you gotta fatten those babies up a little. I did mine, and test chambered a 85gr penetrator round without a hitch. It's really short. 220's feed well too. But the pathway has to match it's function and smoothly.
My first ar had feeding issues i found the barrel extension had burrs on the feed ramps that were the issue a rat tale file and a dremel buffing wheel fixed it but now I know to check for that before accquiring another.
Trying to find out why my new Stag Arms Stag-15 AR is not feeding the rounds when I try to load the first round. Rather slingshot or bolt catch ... The round gets stuck on the the ramps and the bolt stops halfway trying to chamber my first round. I half to recharge the handle and it works after that (pushing the round the rest of the way). I thought it was cause my spring or buffer was no good. None of my other AR pistols do that tho. However my other AR'S are 7.62. I think this is my problem here. Also I think my PMAG doesn't present the round high enough like my 7.62 DURAMAG.
Absurb paying all that money for a high end part and the company cant even do the job correct. Its rare nowadays to find a company or even a person who takes enough pride in their work to do things right. Instead they just take the money and put out poor parts with terrible QC. Pay a premium only to have to pay a gunsmith to do it properly. Makes me question buying from criterion now.
That’s interesting. I understand that individually, each of those companies make quality parts. When we talk about specs & tolerances, I’m not sure where they are derived from. Assuming the tdp? With that said, I don’t think that barrel or upper are used in government weapons. That aside, it’s entirely possible / plausible for every part to be in spec, yet the weapon not function properly? Is that why usgi manufacturers have government inspectors randomly test completed firearms?
thank you for explaining this. I have the very same issue with a new Picketts Mill Armory upper. I have emailed them but no response 😡
Who?
Laughs in AK.
Aks won't run if they aren't properly headspaced.
Thanks Chad
What is your going rate for doing something like that and how do we make arrangements to send you something? I used a different upper when I encountered this (also all quality components), but wonder if I should just have this process done.
I have an issue with my PSA 10.5” upper. It chambers fine but when you go to cycle it manually or fire it, it locks up and won’t eject the round and it needs to be mortared to get the bolt free. What’s my issue?
That's a whole lot of goop in there. Good lord. Looks like brake grease.
You must be new to chads lubrication method
I have a Ballistic Advantage barrel on a Geissele reciver and it has a slight step like as shown on this video but it’s feeding correctly and I have no issues with it up to now. It probably has 200 rounds through it at this moment. Would this be something to worry about? Could it be a issue later? Should I change the barrel out?
Is there anything you would do to the receiver to help feeding or is it not necessary?
I've got this issue on my Aero m4e1 enhanced upper, ramps are clocked to the left with overhang. I'm going to dive in today and see if I can fix it.
I've got an A2 upper with no feed ramps? Do you recommend adding them?
good video sir, you are a wealth of info, thank you. i have found that comparing a FN to a BCM to a PSA, the BCM upper always wins hands down in the QC fit and finish and indeed in the feed ramp area as well. the 3 uppers i mentioned, the bcm one has the best looking m4 feed ramps, they look like they were either polished or machined so they had the appearance of a mirror right from the factory.
Kinda puts a damper on wanting to make work area, buy ALLL the tools, all the major and minor part groups and all the high end, custom, hand selected components and pieces for the perfect build only consisting of the best of the best brands from the stock down to the smallest roll pin tip to butt, top to bottom. Just might not be worth the time and expense after all. $$$$ and still have problems 🤔
Do you have a video of you performing the repair??
What makes it the barrel that's cut wrong and not the cuts on the upper receiver? 🤔
What r the results on the rounds mine gets scrached on the tip going quarder down the bullet due to this?
What if the problem is reversed? And the barrel extension ramps are just shy of the receiver ramps? As if too short. The extention index pin is fully seated in the notch and barrel nut is torqued to spec. I have this abnormality with 3 uppers. All bcm assembled upper receivers and 3 different barrels. A Centurion, a bcm and a Daniel Defense. Seems like a bcm problem to me. Any issues that anyone can forsee?
I had a feed problem in a ruger. It wasnt the gun. It was the mag holding casing too long causing a jam. I switched to magpal clips and no more problems.
you mean mag not clip right?
could you round out the feed ramp with a diamond dust oval burr while keeping the barrel installed??? I think so..just saying i might attempt it.
You will likely remove the anodizing off the upper receiver ramps if you do that.
Not good.
It's your gun so do what you like
My PSA gets rounds stuck in between the lugs themselves, what causes that?
Will that stop bolt from seating in barrel
This made me grab all my rifles and start inspecting them! Thank you Sir for another great informative video!
Yea so I thought for sure this was my problem but I put the wrong bullets in didn’t even know 300 aac blackout was a caliber I thought it was a all black ar
have the same problem with a PSA upper I just bought for a build, Geez the one shown on the video is awesome compared to mine!! I put a mag full of ammo in and tested it before I would actuallt shoot it, you name it it did it, FTF, FTE, DOUBLE STACKING, It takes the cartridge right into the barrel upper, the ammo had gouges and one bullet actually went back into the cartridge which put gunpowder everyehere!! gonna have to send it back, from what i've heard thats gonna be a delightful event ! I'm sorry to all the PSA folks out there but this is not a good quality rifle or componets, i've always been leary about PSA but I finally drank the Kool Aid and very sorry for doing so. I have a Bear Creek Arsenal upper that is 10+ better then this PSA upper, better quality all the way around, the charging handle is..well lets just say my wife have better quality cooking utensils, I hope this is not gonna be a big drawn out procedure but probably will, not to mention I destroyed about $15 worh of ammo... well the bright side is I dint just go out and shoot it, I may have gotten Injured or worse
As the video said you'll potentially these problems regardless
For instance i know people who have PSAs thst are perfect
As seen here a high quality part has a serious issue
If you aren't even going to listen or think why comment on this shit? The reality is it doesnt matter if it cheap or expensive big brand or not all of them are prone to fuck ups instead of going "yep got the most expensive part on the market" take the time to actually check your part and realise it can be a fuck up nomatter how much you spent
I'm having that issue with a PSA 6.5grendel. I'm waiting on PSA to reply. It's been a weeks already.
Why would an issue like this not get picked up in quality control inspections at the manufacturer? Clearly, I am missing something in how these things are built.
How do you know all of the components are within print tolerance? Just because they are reputable brands, doesn't mean something isn't out of spec.
curious as to why the contouring couldn't be done without removing thr barrel?
One would not wish to remove the finish from the softer receiver metal and expose the aluminum to the steel risking cross contamination resulting in corrosion.
@@ditzydoo4378 gotcha... makes perfect sense. Thanks.
@@boss350z5 ^_^ your welcome
@@ditzydoo4378 Is there a problem with lapping the face of the receiver, then?
@@TEXwithNODS Three fold: 1, the receiver feeding guide grooves are already larger than the barrel feed grooves and therefore do not require the removal of material. 2, removal of the finish from the aluminum coming into contact with steel will cause the aluminum to corrode by means of electrolysis. 3. Since the barrel simply slides in and out of the receiver when the barrel nut is removed there is no need to while contouring and test fitting the barrel feed ramps to said receiver.
Where did you get that skull magazine pin
I have them available on my webstore.
Kitfox made them for us.
Why not just add a shim between the barrel and the upper? If you could properly gauge the offset problem on the ramps, they could possibly line up correctly without physical grinding.
That is what I was wondering.
Pushing the barrel forward can allow the carrier to travel further forward.
If this happens the buffer retainer can impact the buffer slightly or with force. Not good.
Thanks for the reply! I guess I should have started off with one would also have to measure the internal dimensions of the barrel extension to see where the extra growth is. To your point.. if the breach face of the extension tolerance is too rearward, this would cause excessive wear on the bolt face. The tolerance that is the root cause should be identified to better know what has to move. I absolutely love gun Nerding. 😀 keep up the great work. Excellent Channel!
Who would’ve ever had thunk
Has anyone ever heard of Pro2A tactical. I was looking at getting a 7.62x39 at setup and they are about the only place I am able to find with uppers available. Any help would be appreciated. Thanks. And as always. Thanks for another great informative video to help us all out
I'm curious why that caliber would be your choice? Nothing wrong with it of course, but it seems like if you are going to go with an "off" caliber AR there are much better choices on the market these days, like 6.8SPC, 6mm-ARC, .300BLK, or my favorite 6.5-Grendel. The 6.8 gives better ballistic performance than the 7.62, and if you're shooting past 300-400 yards the Grendel is a monster out of the AR platform. This day and age you can get most any of them for reasonable prices (when stores had ammo anyway) and with their popularity if you realod brass there's literally hundreds of combinations you can make to really fine-tune your preferred load.
@@TheFishE77Official I’m looking at 7.62 x39 because I already have other calibers and at the moment 7.62x39 is the only ammo still available. I don’t want to shoot it all my 5.56 and 9mm and I’d still like to be able to shoot on the weekends. I can get 1000 rnds of steel case for about 350 so I can shoot and not worry about burning up expensive and dam near impossible to find ammo. This rifle also isn’t for hunting or defense it’s just to target shoot and have some fun I’ll be inside of 150 yards at pretty much all times. Even I did hunt with it where I hunt I don’t get shots much past about 50 yds on average.
@@icantsaywhat Fair enough, and hey you can never have enough guns! Give a look around sites like Gunbroker if you're needing to feed some of your others, plenty of ammo to be had for all calibers. I just picked up a case of 250 rounds of Hornady 123-grain ELD Match 6.5Grendel for not much more than regular retail. I've been finding Wolf Steelcase Grendel ammo super cheap too, and in stock pretty much everywhere. I'm sure you could grab a deal on 7.62 there.
@@TheFishE77Official thanks I did not even think about gunbroker for ammo
My centurion barrel has this issue
This could be my issue, I may need your assistance. I'll get back to you after further inspection.
What is the hole opposite the ejection port ?
That would be the Cam-pin clearance cut out.
@@ditzydoo4378 it just looked like it had jb weld all over it lol...
@@LL-be3rh It was rather dirty at that. >_
I had Core 15 rifle from a few years ago that had this issue as well as multiple others. Easily one of the worst rifles I've bought and I'm thinking due to the Sandy Hook scare. The feed ramps on the barrel extension severely overhanged the m4 feed ramps of the upper, the wall thickness of the lower receiver was thicker on one side, and the rifle was heavily overgassed, it ejected shells at the 1230 o'clock position with shells marring the handguard immediately in from of the ejection port, recoil felt like a light 20 Guage shotgun.
This is either massively exaggerated or outright fabrication but it gave me a good laugh either way so thank you for that
@@royrogers3624 the exaggeration was the 20 Guage part, it did have extreme overgassing though. Everything else is spot on, definitely a lemon.
Hey I know that upper!
Is this your upper? Just curious what's up with the catch for the charging handle, looks like it's really worn in.
@@tristanjeno4890 No idea. It’s been to the range once and I didn’t use the charging handle much.
Carbide bit and a Dremel ? Lol
Looks like somebody lapped the front of the upper receiver too much as it appears the entire barrel is sitting too far in the receiver
I have pulled it apart. It wasn't lapped.
I have a question, but in reviewing the comments (in order not to be redundant) which have been made over the past 2 years, I see that you don't answer questions.
That's unfortunate.
Well shoot! All great parts and still a major issue. Can you show us the process of this being fixed?
ruclips.net/video/Kxz8teLbEPc/видео.html
Another Fabulous Video.....Thanks
I found the video educational. Thank you.
Thanks for sharing this Chad
Are those rubber bands mil spec?
Love your videos
One of the reasons I prefer non-feed ramp upper receivers when building an upper. I use a Dremel with a Cratex bullet shaped bit and polish the ramps on on the barrel which also causes the lower to polish in perfectly matching ramps.
One of the reasons he is pulling the barrel to do the feedramp work is that he doesn't want to cut into the anodizing. The bare aluminum is much softer than the anodizing. Was glad he mentioned it because ive noticed the same and stopped removing the anodizing on any bearing surfaces when doing Cerakote. It leaves a stronger surface. Probably not a huge problem but with heavy use bare aluminum feedramp on the lower will land you with this snagging overhang.
Peace Geek has non feed ramp uppers
You don't want to cut out into the uppers hard coat anodizing.. Cartridges will ding it up more and cause the same hang up issues like Josh said. Better to just remove the barrel to polish and match the barrel extension ramps to fit the upper m4 ramps. Sotar shows a video of this with a sons of liberty upper
Great example.
can you do BCG grinding down, becuz i got a ks47 and i wanna make other bcg fit like psa ks47 bcg
Have you ever done an examination on any LWRC rifles? I have a LWRCI-DI 556 AR-15 and it has a unique type of bolt. There is no separate gas key; it is somewhat integrated into the bolt body with only a additional tube that is roll pinned into the carrier. Was curious how this would compare to other manufacturers.
Chad,
Looks to me as if the upper ramps are lower that the M4 extension ramps, which to me would be the "worst case" scenario. Please do a video on how you fix this. I am extremely interested.