Cutting The World's Longest Rifle To Find The Perfect Barrel Length
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- Опубликовано: 1 сен 2022
- What is the perfect barrel length, and how long is “too long”? In this weeks video we show how barrel length affects bullet velocity.
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Why 308? I feel like 6 or 6.5 creed would have been much more useful, or even one of the prc calibers.
I’m not trying to be mean, this is an honest question.
Funny men!
Joining two barrels together so that the rifling matches perfectly at the correct torque setting is NOT a trivial job. Very well done to the machining guys
@Yuck Foutube the barrels were drilled and rifled separately and the attached together. The rifle was lined up perfectly
Yeah, that's a slick little engineering job they did.
@@ryanmclean3326 Why? Why would they do it like that?
@@sawmaster6095 Because you can't get barrel blanks as long as they needed, rifling machines can only handle so much.
Absolutely..Great Craftsmaship/machining Guys.
Love the folding stock at 01:41 for better storage LOL 😂
It would be kind of cumbersome without the folding stock. LOL.
And the 3 bipods, had me dying.
Aids in concealment!
It's got takedown 1/2 barrel at full length? No, but thought were rifles with more than one quick connect like twist clamp type systems at base or after market devices to change barrels that are overheated? Didn't know was so difficult. is 5.56 Nato 20-24" bet know. or link to calibers?
I'm admittedly not knowledgeable on gun stuff! Just a cool video!
This also makes the rifle a good choice for your backpack or concealed carry
6:15 this shift in point of impact is because of the barrel crown. when you cut the barrel crudely like that the crown isn't going to be perfect so it throws the shot off.
I was thinking the exact same thing. At least they could've hand drilled it on the spot, but it wouldn't be as precise as a lathe. Shoot, even a small hand file would help, I guess.
Came here to say the same.
I'm surprised they didn't re crown w cordless drill at least.
Even a hand reamer would have made a big difference.
Yeah.. here in germany we have air rifle stands at fairs and those rifles are always beat to shit and have on purpose badly cut crowns~ And if you ask the store owners in which direction the crown is cut they always tell you to fuck off and often enough you aren´t allowed to shoot anymore. Like.. dude, a 10" Barrel air rifle even just shooting 4.5mm round ball having trouble at 2 Meters.. don´t tell me that "gun" isn´t manipulated to be inaccurate af.
Hey folks, I did the same thing for 45acp . My results mimic yours except we did see a slow down. This is likely due to scale. Turns out even at that length, for that caliber you were still too short for the friction to slow the bullet. Theoretically as barrel length increases we expect the velocity to climb, then stabilize for a good bit before declining.
Good stuff
Makes sense that .45 ACP's smaller propellant charge would peter out sooner than .308 Winchester. I'm actually somewhat intrigued about how absurdly long the barrel of one of those overbore magnum cartridges would have to be before acceleration plateaus.
😂 Please tell me how your results “mimic” theirs??? When you said in the very next sentence that you did have a velocity drop at the longest length! 🤣 I don’t think you know what the definition of mimic is. Maybe the term your looking for is meme? Your results are a meme of theirs! 🤣 🤣 😂
@@hardtarget2359 you aren’t following
@@VSO_Gun_Channel fancy seeing you here
Did you upload a video of it? I would love to see that
The results would have looked much different if a much slower powder had been used. The factory 308 ammo likely uses IMR 4064 or RL15 or something in that burn rate. If you handloaded ammo and used a much slower burning powder, like RL22 or Retumbo, then the slower burn would perform much better in the super long barrel, as the pressure would stay higher for longer, thereby increasing the acceleration time for the bullet.
I also wondered if tightening the rifling progressively down the barrel would make much difference to make the bullet spin faster
@@sinephase that would actually slow down the velocity. Tighter twist rates generally result in slower velocity, all else being equal
@@sinephaseI have considered this; perhaps progressively increasing the twist rate would help maintain a flatter pressure curve. Theoretically it certainly would, but I suppose the real question is if it would be enough to make a difference.
bravo
There are very few videos on RUclips that I wish were longer and more in depth. But I felt myself wanting more data, group sizes, shot placements, etc. Great video and cool concept.
Thank you! Glad you enjoyed it.
Group size doesn’t have to do is barrel length it has to do with him, screwing up the crown with the bandsaw ever heard of taking your barrel in to have a crown so that shoots properly
Very interesting. Reading the chart, the sweet spot without the rifle being ungainly is about 24.5 inches - exactly where CZ has their 550 Varmint barrel in .308 You have to go approximately 40 inches to get any practical increase in velocity, using the same ammo. Perhaps CZ knows what they're doing. ; )
Yes they do their yob well
* CZ had
new CZ 600 has less options and shorter barrels. 223 rem, 300 win mag & 6.5 prc is 24'', 30-06, 8x57 & 308 is 20'', 6.5 cm is 22''. Quite dramatic cost cutting.
@@shveril9513 A lot of people prefer a shorter barrel for other reasons. Many people are willing to sacrifice a little velocity for increased barrel stiffness and overall handiness of the rifle. 18" barrels became all the rage for "tactical" .308 bolt guns and if maximum range isn't the goal, then it's probably a very good tradeoff. In the end, rifle makers need to sell rifles, and to do that they need to give people what they want.
At some point the increase is minimal so a jump can happen in short barrels let's see 5.56 a 10.5 going to 16 inch with 55 gr is 2100 fps while from a 16 inch it increases to 3000 fps that 900 fps faster so that's 163ish fps increase per inch added however going to a 20 inch that velocity increases but only to 3200 best case scenario soooo 50 fps per inch after 16 inches so more weight and longer rifle for only that gain not really worth it for some people so why bother going longer if you're not gaining enough to justify the longer barrel
@@jwilsonhandmadeknives2760 some bandleaders like the 16 inch rifles because theyll load their rounds hot in 308bfor example and be hitting 18-20 inch velocities with their hot loads
Appreciate all the time and effort you guys spend doing these crazy experiments most of us can only dream of!
This is awesome, great job. And kudos for teaming up with Bob Jury, he’s a great guy. I’d love to see this test done again with a cartridge with a lot more powder behind it, like a 300 Norma, 30 Nosler, or 30-378 Wby. Would be really curious to see what the graph looks like when there’s a lot more ooompf behind it than a 308 Win. Totally understand why you chose the 308, though. Far more relevant test to what larger numbers of shooters are actually shooting.
: Additionally, for the purpose of understanding the science / physics test some rounds that are UNDER loaded with powder, say after standard, then; 84%, 71%, 59%, 50%, 42%, 35%. at the longest length, and graph the results. As you cut the barrel shorter, maybe only ones with Std, and 50% powder load.
@@johndavidwolf4239 So they can get stuck in the barrel😮
@@catherineharris4746 No, Start with the Std. load, then work your way down, plotting as you go, if the plot line appears to approach zero for the next lower round, stop, even if a round gets stuck and needs to be pushed out, (I heard that there is this thing called a "ram rod" that is used to push bullets through barrels, and that it was invented centuries ago) that it is a data point, helpful to better understand the ballistics of that caliber.
@@johndavidwolf4239 💡Wow I could of sworn that ramrods were for muzzle loaders that were the only guns used centuries ago. I didn't know they had and used higher pressure center fire rifles centuries ago, and were able to push a stuck slug out of a rifled barrel😕 Are you sure they had these same center fire rifles that required 50k to 60k psi to force that slug through the barrel, and is it really that simple to use a ramrod to push a slug out of a barrel that took that high of pressure to get it stuck there? Dang I guess i just learned something new👍
@@catherineharris4746 : 1) There are shooters that use muzzle loaders today. 2) The 50k to 60k psi in not needed to force the slug through the barrel as much as to accelerrate it to the supersonic muzzle velocity in modern rifles. Unless it gets stuck just a few inches from the cartrage, it will have already been swaged to the barrel and the rifling and should require no more than a few pounds of force to push it out.
I've been using your stuff for years, and it's worth it.
As a former barrel maker myself, it's nice to see how you guys actuality understand what's going on. And the data to back it up.
Oh yeah, they really know what’s going on if you’re a barrel maker, you know that your crown the barrels nicely so the shoot accurately spend extra money to take your rifle and have it crowned properly these guys and cutting a barrel with a bandsaw isn’t going to make the gun shoot terribly because he made the comment about the barrel length and accuracy. The crown is everything with accuracy at the length of the barrel so much but yeah, these guys are experts just like you.
I am so happy for RUclips. I have seen this test done twice before but no one recorded it before computers. Now there is proof for all time! Great job and well done.
Died laughing at the 3 bipods and then the immediate cut to him folding the stock to stow it 😂
The production value on these is insanely good.
Thank you so much for the kind words:)
Really love that the MDT team put so much back in to the sport not only in R&D, Sponsorship, but like this vid testing thought and ideas that shooters have
Top work team.
I would venture to guess that the left-right deviation you saw as you cut it might have been due to the crown not being perfectly square with a bandsaw finish. I have seen rifles with less than ideal crowns do some wild stuff. Great video!
It could be, but there has been some testing done on this subject that says otherwise, but it was still a fun test!
@@MDTTAC a great shop tool for you guys would be the Manson crown cutter set up in carbide. Manson Precision Reamers setup with a simple cordless screwdriver would give you as near perfect a crown as you can get in minutes for each cut length. Many of us keep copies of your data points because we can trust them. And true accuracy testing means a proper crown. Cheers and thanks for all your hard work everyone!
@@MDTTAC It’s too late now, but it might be interesting to do this again with high speed photography of the barrel movement in vertical and horizontal axies (and possibly twisting…). Maybe even a little accelerometer on the end of the barrel.
In a practical sense guns getting too long is a problem, but bullpups exist and adding +10-12” that way is plausible.
This was 308 correct? I should sit down and run the swept volume in barrel vs case volume numbers.
The bullet groups shifting left and right each time you cut off more barrel is from the crown not being perpendicular to the bore
He just wasnt deburring lol
@@Moe_lester_ sure was deburred after the first shot lol
That's awesome, thank you for collecting and sharing that data. Several years ago I published the results of doing something very similar with a shotgun. I started with a barrel length at 36" and cut it every inch, measuring MV with slugs, and every 6" in group size with buckshot. We ended up with a 6.875" barrel when done. The results were surprising and I'm still contacted about it today. It was published in Small Arms Review Magazine.
Doing the Lord’s science!!! Keep up the great stuff!!! This needs to be the “What if” series to keep great work like this going!!!
Thanks for doing this! It answers all the questions I have about barrel length.
Lots of work! Thanks for putting it all together 👍🇨🇦
High quality video and editing. Nice job. Thanks.
Thanks fer sharing an AWESOME experiment in a timely video - You guys are the best !!
Awesome video, unexpected results for sure. Earned my sub.
Interesting test, I bet you spent the better part of an entire day performing this cut-down barrel test!
Thanks for this awesome build and test !
Hey MDT, I love how you put out these awesome videos and actually prove what would happen if. Can you please make a video proving if there are any accuracy differences between a prefit shouldered barrel and a barrel installed with a barrel nut. Use the same manufacture, same barrel profile and twist rate. Make it a five shot group instead of a three shot group. And shoot out a little further to really show if there is any difference like 300 metres or 500 metres. BTW have your XRS chassis and love it. Please make one for a Remington 700 long action footprint. $$$ waiting ;)
We will give it some thought, and likely there would be no difference. We already have the XRS for a Remington 700 LA out and ready to ship! mdttac.com
/xrs-chassis-system/
Please please do the comparison. Gunsmith are saying the ONLY way to have a barrel installed properly and achieve maximum accuracy is to have it shouldered and installed by a competent gunsmith. They say that prefit off the shelf shoulder barrels are still off by a few thou and are not recommended and that they cannot make a prefit from the receiver drawings because the custom receivers still have variances ( and I am talking custom receivers like Defiance, Zermatt Arms… not factory Remingtons). Then the big joke is the barrel nut system ( Savage style barrel install). The gunsmith says that is not the proper way to install a barrel. It is done to cut cost. It is a lazy way to install the barrel. You will not get maximum accuracy following this method. As you tighten the barrel nut you actually create a sides way tension on the barrel and affect how the barrel interfaces with the receiver. Please prove this theory right or wrong.
Going to place an order for that XRS, is the mag well CIP, I need 3.850” ?
Thank you MDT!
@@kten237 It depends what your final accuracy goals are. If you want to succeed in Benchrest you will not get there with a prefit. Will a prefit meet the average PRS shooters loading and accuracy requirements? Absolutely. Does paying $75 more to get a gunsmith to install it hand fit and guaranteed create additional value? Guess it depends if you want the support, guarantee and absolute best fitment. For the most part a quality prefit will outshoot most shooters. But from a value proposition, if you are paying $4500 to build a gun, why not $4600 and get the best fit possible and local support and a guarantee. But all precision rifle builders are not created equal either.
@@kten237 Its something we can look into, but our standard Remington 700 LA inlet takes a 3.715" magazine.
@@kten237 Stop talking to that gunsmith. He sounds like an idiot. Criterion prefits do perfectly fine with barrel nuts. Plenty of shouldered prefit barrels out there for a pile of actions that shoot great as well. Hell even mass produced savages can shoot great if you get a good barrel.
being a physics guy... I think whats happening here is that the powder burn/ barrel pressure starts leveling off at around the 46 inch mark. one has to remember that the more barrel that the bullet travels through, the bearing surface of the bullet is also wearing away so the resistance is also dropping more and more as it travels down towards the muzzle.
Plus, if you are going to be using a really long barrel, you would want to handload to match the powder for the barrel in question... For this long of a barrel, it's quite likely that a slower burning powder would have been more appropriate... Of course, you are limited by your case size so that even will a full compressed case of some particular powder, you might not be able to take advantage of all of the additional barrel length...
@@seanseoltoir true... but not too sure case volume is the limit... its also the pressure the case and action can withstand. at some point the primer pocket and case head will deform. I do agree that handloads with the slowest burners would have been interesting.
@@renaissanceman5847 -- Yes, that would be an issue if you were switching to faster powders, but if your starting point is the normal rifle powder load, then a slower powder of that same load is not going to exceed the pressure of the original load... At some point, you get to a powder that is slow slow that even with a compressed case load of it, you cannot exceed the pressure rating of the gun... For example, I've taken .50BMG and 20mm powder and put a full case of it in a 10mm handgun cartridge as a test and fired it... The powder will just not burn enough in that short of a barrel to do much of anything... It won't even cycle the action on the handgun... It does make for a rather quiet (and slow) round... :) On the other hand, if you were to put a case full of Red Dot in a 10mm cartridge, you would most likely have a gun that "disassembled itself" in your hand...
I’m 4 years into my physics bachelors and I tried to make a 150 psi air gun that was fully optimized for shooting a 15 grams projectile. When I did the math for the optimal barrel length I was surprised that it turned out to be roughly 2 meters. At first I thought I miscalculated something, but after going through it with an engineer and a mathematician friends of mine, turns out I was right. I didn’t end up building it due to legal reasons lol but I’m glad to see this video. Thanks for making something I couldn’t make myself.
Very fun and informative test! Thank you!
Great video. Quite interesting. I suspect if you went with larger magnum cartridges with slower burning powders you would see it speed up even more.
very cool work.
Cheers to everyone who made this happen
Jim
1:41 - The irony of a folding stock on a gun with a 6 foot barrel. lol
You tailor the handload to the barrel length available, picking a slower powder for a longer barrel. The same load will perform differently in a 20" vs a 30" barrel.
9mm handgun vs 9mm carbine is a good example how different the same calibre can perform. If handloaded properly.
That was an epic test!! Thank you for the info!! I guessed 2750 at 6ft but I really thought it would speed up more to like 2900ish around 36-40 inches of barrel. Interesting find. I wonder if a larger case capacity cartridge would yield similar results across the board or if this was a function of combustion chamber size vs fuel?? 308 was a great choice though as we can all relate to it and understand it well. Love this test! Thank you!!
I'm very impressed with the content on this channel.
Thing i like about these types of experiments is that they often reveal just how experienced and knowledgeable the manufacturers are.
Loving these videos
I love MDT. I have a ACC stock 2x10 round magazine,muzzal brack and a CKYE - pod gen 2. And i love everything. But the tests you guys do. Well done. Just like videos to be longer. You should have a showroom where you have all your tests
What an astonishing, informative and downright funny video. Shooting Barricade with that would be like walking the course twice :) The multiple Bi Pods must be a nightmare. I get into enough trouble with one :/ I truly enjoyed your commitment to the ridiculous extreme in the name of knowledge.
Epic, absolutely epic. I had a blast watching this video. It's scientific and funny at the same time. Thank you so much for this.
I like these types of videos. Great work!
Great vid, as always. Nothing beats theory like parctice!
Absolutely ridiculous...and I love it. Please keep this kind of experimentation coming!
I love yalls channel 👍
Thank you for all the expenses involved in this this is awesome
🤣🤣🤣 i love these kind of videos you guys do! So entertaining and interesting!
love the content your putting out!!!!!!
I appreciate the folding stock for maneuverability and ease of carrying
Another informative video, and not just for fun. Thanks.
Excellent content, thank you!
Absolutely awesome! Must be a great place to work.
I'd love to see how different powders, play into this experiment.
Awesome video!
Very cool seeing the end point data!
Terrific video! I’m going to gout on a limb here and say that the optimal barrel length is the length at which the increase in velocity is 1% of the muzzle velocity. So, for a bullet going 2500 fps, when an additional inch gives you no more than 25 fps, that is when you stop.
I collected some data from other cases where people have cut down barrels such as in this test. It seems that with .223/5.56, the velocity from a 20” barrel is about 3000 fps and the gain in velocity from a 20” to a 21” barrel is about 29 fps. Some calculations I did suggest that the optimal barrel length for a .308 would be 21”, 22” for a 7mm-08, 23” for 6.5 CM or .30-06, 24” for .243 and .270, and 25-26” for magnums like 7mm Magnum and .300 Win Magnum. To get the best out of something like .338 Lapua or .300-378 Weatherby you’d want 28” to get to that 1% velocity per inch mark.
No doubt, a lot of work went I to this. Great content!
Really cool video, thanks
I'm a minute thirty into video and 🤣 this is the greatest thing I've ever seen, its like a live meme or something 🤣, "more barrel the more accurate", "when you take long range too serious". Great stuff guys keep it up.
What an experiment! Pretty rad!🤘🏻
This is easily now going to be one of my favorite videos to show friends and family. We hunt a lot, my father's choice has been .30-06 for decades, mine has always been .308 WIN. You dedicated a whole video to an idea of "why shouldn't we" rather than "why should we". Interesting as heck, now I'm left wondering what sort of difference you'd find with newer high performance type cartridges. Hint hint, wink wink, cough cough.
Great video. I had wondered about this.
that is so interesting. there's barrel harmonics at play here. to the point where cutting small bits off the front change how the barrel is moving and causes shifts to the aim.
This was awesome. Would love to see the calculations and work done to match up two barrels
That would an interesting video by itself.
Great video. I been saying longer barrel faster speed for years and it is cool to see video proof. Seen way to many people claim short barrels are faster and better when my personal experience has been the same as this video.
A lot depends on the cartridge. For instance, velocity vs barrel length is much more of a factor with 22lr
@@John-uo1qf wrong, but believe what you will
@@Randy_Cox Point me to the data
I have never heard people say shorter can be faster except in the airgun world with spring-piston airguns where the gas volume & energy is extremely limited. In any practical rifle using a rifle cartridge, longer is faster. If it makes a bang at the muzzle, there is plenty of energy remaining.
Awesome video 🎉
that was sick, i would love to see how a PRC round would run out from a barrel that long. You would think that the farther the bullet went down the barrel it would lose back pressure, but it looked like it picked up. Very impressive.
Back about 20 years ago I shot a long range match at Oakridge TN. One guy on the firing line had a barrel so long I thought it came out of a cartoon. The guy told me how his rifle was going to get him the win that day. Of course no doubt he had a very fine peep sight adjustment likely less than 1/8th MOA and also likely an awesome sight picture but the guy still failed to win. I know because I won with a 24 inch barrel .308, shooting a 197, 196,, and a 195. I saw the guy as I left the range to thank him for all his tips which helped me win.
that was awesome thank you
I’m loving these scientific yet entertaining videos
This is really cool, I'd love to see what a subsonic caliber would do with extreme barrel length perhaps it you could achieve a hearing safe result
I've always wanted to see this, I hypothesized that most centerfire rifle cartridges generate more than enough pressure to keep the bullet accelerating for far more than typical barrel lengths. It'd be even more interesting to see this test done with super high-velocity underbore rifle cartridges like .30-378 or .220 swift since smaller bores really need the extra barrel length to create more volume for the gas to expand and let the bullet accelerate under a higher pressure than a larger bore allows for. I think you could go beyond 5000 ft/s with this long a barrel, up to whatever the maximum expansion velocity of the propellant gas is.
Awsome awsome video and idea!!!
This is excellent. Inquiring through the scientific method.
These experiments are fun to watch.
Ok, who on the market is making a 45" barrel? Cause I NEEED it. 🤣🤣🤣🤣
It can be done!
They are harder to find than you might think!
I've never seen an instance where you lose a significant amount of velocity from excessive barrel. VSO even did testing with a ridiculously long barrel on a 45acp and it mirrors the curve you plotted.
As much as I dislike VSO, his content is pretty accurate on data points.
I'd be very willing to bet a large sum of money that you'd need a barrel longer than 10 feet to start seeing any significant dip in velocity, and even then, I'm not so sure.
My only reservation about this would be in a gas gun where gas could potentially flow backwards, and create suction once the round pushed so far out into the barrel, and gas had already cycled the bolt carrier group.
Ideally, you'd push your gas system further out to counter the extreme dwell time. At a certain point, though, you wouldn't have enough pressure to cycle the rifle... so having a gas system would only serve as a hindrance.
I did similar test with foam dart toys, as I was into high performance nerf with smooth bore aluminum barrels. With air speed constant, or this case powder burn rate. As long as there is enough air volume to clear the barrel, there really isn't much speed loss with a longer barrel. Now if you could develop some custom load for this 6 ft barrel, that would be extremely fun.
Lilja did some interesting experiments on this subject, starting at 4 feet, and then removing an inch at a time. One of the more interesting pieces of data was the fact that muzzle velocity didnt drop consistently each time they removed an inch. Several times the velocity seemed to "stick", until the barrel was cut down two inchs or more, then seemed to drop more than expected.. In one instance, velocity average actually went up slightly.
The other interesting piece of data was the practical weight limit for conventionally mounted barrels seems to be about 7.5 lbs. Beyond this, barrel "droop" starts affecting harmonics, and thus accuracy. The way around it is something that 1000 yard "heavy gun" shooters have been using for decades: Barrel Blocks. They not only provide a stiffer means to attach the barrel to the rifle, but because the section of the barrel where it threads into the action is rigidly clamped into the block, it effectively "shortens" the barrel from a harmonics perspective, making the barrel behave like it is much shorter than it actually is, increasing accuracy. The downside is, of course, size, weight and cost, which is why you almost never see barrel blocks being used outside of heavy gun(custom rifles that cost thousands of dollars and have a weight limit, if any, of 100 lbs. Most of the rifles in this class seem to weigh between 60-80 lbs)
Impressive test. Very cool.
Great content! I’ve missed what twist that was. Just wondering if more aggressive twist will affect things
The point is not only V0 speed but SD and group size too, a combinantion of factors related to the speed you shoot not only round count.
You guys are Madlads. I love it
👏👏👏 very interesting video good job !!!!! 🔥🔥🔥
Love the 72" barrel. Have you thought about hand loading and changing the powder dependent on the barrel length? Since the velocity decreased with a shorter barrel, change to a faster burning powder that maintains the same case pressures. My thought is that the velocity decreases with shorter lengths due to not being able to achieve full powder burn to pressure ratio.
Love this video. Try it with a 300 PRC next.
Great test, busting more myths. Were you recording accuracy?
Beautifully done ! Question: why didn’t you recrown the barrrl after each shot to BBSs see if grouping changed?
This made me giggle audibly. And it answered a question I've had since I was a kid.
The real key to this test is the factory powder used, which is designed for much shorter barrels. If you used reloads with a slower powder, I think you'd have seen a much greater increase in velocity in the longer barrel
I agree, it depends on the distance down the barrel when the propellant is fully burnt and the subsequent distance when gasses maintain pressure before reducing. A slower burning powder may very well increase the velocity in this barrel test.
From muzzle break to barrel length, you guys ROCK.
I've always wondered about this ever since I watched the Trigun anime and saw the scene with the sniper that used a rifle with a ridiculously long barrel.
I would love to see this same test run with an overbore cartridge such as the 22-284 which has a large powder capacity and a pretty small 0.224 bore diameter, plus the 22 centerfire cartridges are making a big resurgence recently. I think the velocities may be even faster as it would give more time for the powder to burn before the bullet exits the barrel. If you were to ever run this test again I would say start with a 52" barrel as there was so little change in velocity between 72" and 52"
This is incredible
Bob made the 22 inch long / 1:8" twist Stainless varmint barrel on my LH Savage 243win that sits in an LSS Gen 1 chassis !
Need to get him to thread and label my barrel though... 🧐
I'm wondering if custom loads with a VERY slow burning powder would have performed better in the longer barrels. Factory ammo isn't optimized for a 40+ inch barrel.
slower burning powders generally need a lot more powder by volume to hit the operating pressures of the cartridge. In short you would need a lot bigger case to hold more of the slower burning powder. you might get away with going with a powder that is a little slower, but just going to a very slow burning powder would not work.
Yeah that's interesting 🤔
@@jonathanrogers9961 like try the experiment again with 300 RUM
I agree that I would have liked to seen this, but I would hate to clear a squib on this thing.
Now the question remains, how ludicrously long does the barrel have to be for friction to begin to have a noticeably negative effect on performance? Obviously you don't gain much after 40 inches, but what does it take to actively hinder performance?
For 22LR it is 22" then velocity starts dropping.
I don't think it is friction only that needs to be considered. As the bullet travels down the barrel, the pressure behind it decreases because the gasses are expanding. Once the pressure drops to zero (I mean once pressure is equal in front and behind the bullet), that is the fastest the bullet is going to go. If the barrel is longer than that it will start to slow down in the barrel.
@@mckenziekeith7434 That plus buildup of air being pushed ahead of the bullet, that was previously sitting in the barrel. Also what’s the pressure at the back of the bullet vs at the chamber differs.
@@Georgewilliamherbert Yeah good point. The bullet will be accelerating and the air in front can't exit instantly so there will be back-pressure from that, also. I guess it is pretty complicated. But I still feel that the volume of gas that evolves from gunpowder combustion is going to be a key part of the equation. And that volume probably depends pretty much on the powder charge (and not on much else).
Yes pressure is dependent on the volume and the conversion of gunpowder to gasses. A smaller cartridge will not be able to push as far in a barrel.
7:01 for full graph. Velocity increase is pretty constant until around 44 inches, after which it pretty much stops. Weird that there was such a spike at 24 inches though.
I would think that was either one or more rounds out of spec or measurement error. Could easily have been recording error.
This type of testing has already been tested by militaries and there's already data available about the limits of positive gains in velocity and energy delivery in correlation to barrel length. There's also information about barrel twist ratio and how it correlates downrange with varying barrel lengths but I don't know much about that information. This test makes me wonder how much your rough crowning is affecting both your speeds and impact points.
Cool experiment but, now what I'd really like to see is the same thing done but with some overbore cartridges like 6.5-300wby or something along those lines to see if there's a magnified difference in velocity or if it scales similarly to lower velocity cartridges like this one