Not an AR pistol guy so what differences are there between the two barrels, other than an inch? I've read that 10.5 inch barrels have more feed problems but haven't seen an explanation.
What is the difference between a 10.5 inch and 11.5 inch barrel AR-15 pistol in 5.56?
- Thread starter gunsnjeeps
- Start date
Shorter does tend to run into more issues as you stated. Usually shorter than 10.5 is more common
11.5 will have slightly more velocity
I run a 10.5” 556 on an SBR which started as a pistol. Tuned to run suppressed 100%. However never had an issue Unsuppressed at 10.5 with carbine gas system and standard buffer/springs etc
11.5 will have slightly more velocity
I run a 10.5” 556 on an SBR which started as a pistol. Tuned to run suppressed 100%. However never had an issue Unsuppressed at 10.5 with carbine gas system and standard buffer/springs etc
I have an 11.3” SBR. Runs pretty much anything I put through it (suppressed/unsuppressed) so long as I adjust the gas block.
Had a buddy slap together a 10.5 and it was picky with ammo, didn't have an adjustable block on it. Can't recall the barrel, but he swapped it and put on an adjustable block, ran like a clock after that.
I haven’t had any issues with my colt barreled 10.3” upper. Running a carbine spring and an H2 buffer. Shoots soft and ejects right about 4:30.
Previously had an aero precision 10.5” upper that ran great too. I think the 10.x” guns have been around long enough to have the kinks worked out.
Previously had an aero precision 10.5” upper that ran great too. I think the 10.x” guns have been around long enough to have the kinks worked out.
I've had both. I like my 10.3 better, but the 11.5's have better velocity. But I can get hits at 300m with it.
Mine was overgassed so I put a BRT EZtune gas tube in it and now it runs great. No gas to the face while suppressed and lower recoil. It was perhaps the best upgrade I've ever had on an AR. I also use the LMT E carrier, and a Vltor A5, H4 buffer, and Springco green spring.
Mine was overgassed so I put a BRT EZtune gas tube in it and now it runs great. No gas to the face while suppressed and lower recoil. It was perhaps the best upgrade I've ever had on an AR. I also use the LMT E carrier, and a Vltor A5, H4 buffer, and Springco green spring.
If you get a quality 10.5 ish barrel it will run just as good as any 11.5 today. I have a LMT 10.5 upper that i have had for well over 10 years and it has no issues. I also never use adjustable gas blocks.
The main reason that 11.5 barrels were popular is because 30 years and back those were the shortest barrels that would actually work. Now days there are plenty of quality 10.5 barrles that function properly, when set up correctly.
The main reason that 11.5 barrels were popular is because 30 years and back those were the shortest barrels that would actually work. Now days there are plenty of quality 10.5 barrles that function properly, when set up correctly.
Ballistics (MV). Blast (flash ball) report over all handling and balance.
Right, lots of stuff come into play. I’m a fan of 11.5-12.5”. That being said my favorite to shoot is still my standard 16”.
side by side my 11.5” is much more “civilized” than my bu
Right, lots of stuff come into play. I’m a fan of 11.5-12.5”. That being said my favorite to shoot is still my standard 16”.
side by side my 11.5” is much more “civilized” than my bu
I have
daniel defense 10.5 barrel with Adam's arms piston system, works great and shoots amazing.
Came here to post I’ve got a braced 9” pistol and after a magazine your face goes numb. Wouldn’t recommend but it fits nice in motorcycle saddle bags so I’ve still got it.
Um.... An inch?
Just because noone else pointed this out...
SIrhr
Just because noone else pointed this out...
SIrhr
To directly answer your question: 1 inch.
Assuming you want more details about technical things and stuff, every 10.3 or 10.5 barrel I have shot from Colt, or whatever, for work has worked with the 62 and 77 grain varieties of ammo. Gas port size is the name of the game as it pertains to felt recoil, timing, dwell time, and all the whatever. I dont know the numbers off the top of my head, but 0.072" is standing out for some reason as the "right" size for a 10.3 or 10.5 with a standard or H1 carbine buffer as I type looking at my beer.
Btw, every shorty I ever shot with a standard weight buffer and m855 always ejected at like 2 o'clock, so an H1 would probably slow down bolt speed and make them eject in the "correct" 3-4 o'clock direction.
May accuracy standards have become "minute of commie" for my carbines, so, ya.
Assuming you want more details about technical things and stuff, every 10.3 or 10.5 barrel I have shot from Colt, or whatever, for work has worked with the 62 and 77 grain varieties of ammo. Gas port size is the name of the game as it pertains to felt recoil, timing, dwell time, and all the whatever. I dont know the numbers off the top of my head, but 0.072" is standing out for some reason as the "right" size for a 10.3 or 10.5 with a standard or H1 carbine buffer as I type looking at my beer.
Btw, every shorty I ever shot with a standard weight buffer and m855 always ejected at like 2 o'clock, so an H1 would probably slow down bolt speed and make them eject in the "correct" 3-4 o'clock direction.
May accuracy standards have become "minute of commie" for my carbines, so, ya.
I'd say dwell time is something to consider. 10.5 (like the DD MK18) are often over-gassed which means that felt recoil is slightly higher and it wears out your bolt a little faster. Is generally rougher on the gun and definitely dirtier. Also, adding a suppressor changes the game so you want to look long and hard at what you are getting and how it will stack up in the future. Not sure if 11.5 have as many dwell time issues or if the ports are similarly widened.
This dwell time stuff has to stop. Properly sized gas port or ideally adjustable gas block and it works fine. When you suppress an extra inch shorter barrel makes a difference in carried length, and that’s a heck of a lot more important than “dwell time”. Just make sure to use an adjustable gas block and it’s a nonissue.
Pretty much, just don't buy some no name barrel and I'd suggest opting for an adjustable block. In this day and age every AR should have an adjustable block imo. On the other hand, if you're not too into AR's I'd suggest buying a complete upper and ask the manufacturer what buffer you should use with it if it doesn't have an adjustable block.
you will not have feed problems from a well built factory rifle. Now if you plan to run suppressed, then gas port size will come into play along with an adjustable gas block. I run a crane spec 10.3 upper and I have had zero problems with it. Also the upper kicks very little gas to the face.
Honestly, pick whichever barrel you think is the best value/deal or looks best with your desired handguard length. The practical differences between the two are pretty minimal. Depending on your intended use, the extra velocity from an 11.5" or the 1" of gained maneuverability from the 10.5" might not be useful. I was trying to decide between 10.3", 10.5", 11.5" and 12.5" - and would have been perfectly happy with any of them. I settled on an 11.5" because I found a decent barrel on sale and I haven't looked back. AR pistols are so common these days, that most of the kinks with gas port size & location have been worked out . Just be sure to go with a reputable barrel manufacturer.
I did a bit of homework a while back and got a million opinions... but 11.5 seems to be the ideal length for velocity. Meaning least loss from 14.5 or 16" etc... 10.3+ seems to be the sweet spot for reliability as 7.5" etc seem to have a lot more issues with reliability, finicky w/ ammo etc. In addition substantial velocity loss vs 10-11.5 etc, as in 2200 fps w/ m193. There is specialty ammo 62 gr sp 77gr etc that don't rely on velocity to be effective, fragment etc.
I ended up going w/ a 10.3 because it was a good deal at the time. I liked it, sold it during all this nonsense for more than the parts cost and would buy another or 11.5" in the future.
I ended up going w/ a 10.3 because it was a good deal at the time. I liked it, sold it during all this nonsense for more than the parts cost and would buy another or 11.5" in the future.
What has to stop? You just made my point by emphasizing a properly sized or adjustable gas block but make it sound like dwell time is not a problem. You just want everyone to stop worrying about dwell time? It is one of the most important things when making barrel selections. What a stupid remark.
So an adjustable gas block takes care of the issue? That's utter nonsense. An adjustable gas block doesn't do shit if your barrel is 10.5" and ported for the gas block at .0625. Only if the barrel is a) short and over-gassed at .083 (like DD Mk18) or b) standard length (16 inches), does an adjustable gas block make sense. You would adjust the gas down to the needed pressure. You can't adjust the gas up to something the porting does not allow.
Last edited:
Well, I just purchased a "Crane spec", 10.3", 5.56, 1:7, 0.070" diameter gas port, "SOCOM" profill barrel. Whatev's. I've always wanted a shorty, so I'll make a pistol and let you know how she goes. It'll be for 68gr+ bullets. As long as it functions reliabily, and pokes holes in things I pew pew at, I'll be satisfied.
Expo Arms Combat Series 5.56 Chrome Lined AR-15 Barrel SOCOM Profile Carbine Length - 10.3"
DetailsThe Expo Arms Combat Series AR-15 Barrels are designed to give you a premium barrel at an affordable cost. This AR barrel is made from Mil-Spec 11595E certified 4150 steel and features a chrome lined bore to withstand high temperatures for a long barrel life. This 10.3” model features a...
www.primaryarms.com
Both barrels having the same carbine length system and properly ported means the dwell time doesn't matter and difference in an inch is insignificant.
This
You may get about another 30-40fps from that 1 inch depending on powder choice.
Well, I just purchased a "Crane spec", 10.3", 5.56, 1:7, 0.070" diameter gas port, "SOCOM" profill barrel. Whatev's. I've always wanted a shorty, so I'll make a pistol and let you know how she goes. It'll be for 68gr+ bullets. As long as it functions reliabily, and pokes holes in things I pew pew at, I'll be satisfied.
Expo Arms Combat Series 5.56 Chrome Lined AR-15 Barrel SOCOM Profile Carbine Length - 10.3"
DetailsThe Expo Arms Combat Series AR-15 Barrels are designed to give you a premium barrel at an affordable cost. This AR barrel is made from Mil-Spec 11595E certified 4150 steel and features a chrome lined bore to withstand high temperatures for a long barrel life. This 10.3” model features a...www.primaryarms.com
You’ll dig it. If you need hunting/defense loads, the 77 Sierra TMK is great in short barrels.
I was specifically commenting about the use of "but dwell time!!!!" in nearly every thread discussing a 10.5" vs. 11.5" barrel. It's often thrown out as a reason you should never use 10.5" barrels and always use 11.5" barrels. I was pointing out that you can resolve the so-called dwell time related issues people complain about simply by designing the gas system appropriately for the barrel length, be that port sizing or adjustable gas blocks, and adjusting the buffer system to suit. One could argue the academics of bolt wear and so forth for ages, but properly set up, it's a non-issue in normal use.
I haven't got 10,000 rifles in inventory and 10,000 soldiers to go run various configurations for a year and calculate failure rates, so perhaps there's some differences at the macro level, but it's not one likely to be encountered by a typical user. A lot of what's in circulation is significantly over-gassed, so you have to read a bit more into the numbers that are sometimes tossed around without consideration for the design intent. Everybody gets hung up on examples with overly large ports designed to run no matter what (or, quite frankly, not designed at all - just the easy mode way of ensuring function without proper tuning); of course they run more violently. It doesn't have to be that way.
Exactly the point I was attempting to make. The only thing you're really giving up is velocity, the muzzle flash/report is going to be horrible with either.
Last edited:
FWIW had 10.5 (LMT) - it was great and all except it would not run consistently with 55 grn steel cased Wolf, unsuppressed. 62 Wolf - no issues. Is Wolf garbage - yes.
11.5 (colt) eats anything under any condition - which was important to me.
10.5 went away.
11.5 (colt) eats anything under any condition - which was important to me.
10.5 went away.
That is as simple as opening up the gas port .002" and that is what some of us have been trying to say for 10 years. The gas port controls everything, a 1 inch difference in barrel length is insignificant.
In your case there is no doubt LMT ported that barrel to run full power M193 or 855 at 58000psi so using Wolf that only creates 52000 psi caused the issue. Port both the 10.5 and 11.5 the same size and both will run.
It's why adjustable gas, IMO, should be standard on all AR15s. It's almost like different variations of the same cartridge produce different pressure peaks and curves! Maybe we shouldn't have a static bleed off for bolt cycling, and instead be able to match the rifle to the ammunition! /dripping sarcasm
Drill the port large enough to cycle the weakest ammunition in a dirty gun, and then add an adjustable gas block. You can tune down the excess gas when shooting heavy loads suppressed, and open it up when you encounter frozen weather with grease on the BCG shooting trash 55gr Wolf.
I would tend to like and agree with what you've said here, except, I highly recommend going with best components matched to the rifle. Obviously, in the extreme, having the advantage of adjusting for "less than worthy" ammo may keep your ass alive. You may never have to adjust it, but if you have to, you can.
I'm probably gonna open my gas port to 0.072" with a carbide reamer. Easy cheesy. I have a SLA adjustable gas block sitting in my parts box, so why not.I would tend to like and agree with what you've said here, except, I highly recommend going with best components matched to the rifle. Obviously, in the extreme, having the advantage of adjusting for "less than worthy" ammo may keep your ass alive. You may never have to adjust it, but if you have to, you can.
The correct answer is always 11.5 if not 12.5.
If you need something where 1 inch matters that much then swap to 300 blk and get a 7-10" barrel.
Support
www.ar15.com
There are a few other test floating around. All of them support the fact that 10-11.5 is significant. after 12.5 velocity gains slow. And again if you need that short. Why not go 3-4 inches shorter?
If you need something where 1 inch matters that much then swap to 300 blk and get a 7-10" barrel.
Support
Suppressed 5.56 SBR Velocity Tests--41 Factory Loads from 10.5", 11.5", 12.5" & 14.5" ALL DONE! - AR15.COM
Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.
www.ar15.com
There are a few other test floating around. All of them support the fact that 10-11.5 is significant. after 12.5 velocity gains slow. And again if you need that short. Why not go 3-4 inches shorter?
Got a Lantac 10.5 barrel. No issues thus far. Have ran 55gr to 77gr. Just interesting to hear that shorter barrels have issues. Hope I don't run into issues in the future. Keep shooting...
Typically with all barrels of the same manufacturer we see 20-25fps/inch of change all the way to 24". In those test using Black Hills 77TMK the 11.5" was actually 3 fps slower than the 10.5".The correct answer is always 11.5 if not 12.5.
If you need something where 1 inch matters that much then swap to 300 blk and get a 7-10" barrel.
Support
Suppressed 5.56 SBR Velocity Tests--41 Factory Loads from 10.5", 11.5", 12.5" & 14.5" ALL DONE! - AR15.COM
Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.
There are a few other test floating around. All of them support the fact that 10-11.5 is significant. after 12.5 velocity gains slow. And again if you need that short. Why not go 3-4 inches shorter?
That inch will give you a little room to play with ammo selection. As pointed out above, Wolf and other Russian steel cased is loaded with a weak charge. Daniel Defense for a while opened up their commercial Mk18 gas ports because people were complaining their cheap ammo will not run in their high end AR-15. Why someone would do that baffles me. BCM still refuses to make a 10.5" barrel because the owner thinks that extra inch is needed for an AR to run properly. On my Mk18 inspired upper the only two parts on that are not BCM are the barrel and sights.
OKay all of you seem convinced that 1 inch makes a difference. Please someone post the formula you use to figure the gas port size . It should consider max pressure created by the cartridge, bore area(volume ci), gas port location, pressure at the port, length of gas port, gas tube length and volume, bolt cylinder volume, total time(ms) to port with a given load, dwell time(ms), pressure drop/ms after the port.
Even with that it does not take into consideration, buffer spring rate, stroke, weight of buffer or weight of BCG but we can assume the same is used for both barrels to simplify things.
Even with that it does not take into consideration, buffer spring rate, stroke, weight of buffer or weight of BCG but we can assume the same is used for both barrels to simplify things.
Last edited:
All things being equal. A 10.5 will run a little harder than a 11.5.
With that being said. I have been shooting a 10.5 mrp for years with no issues.
So, Ive been shooting a DD Govt Profile 1:7 5.56 10.3" barrel on my SBR for a few years. I just built a second upper with a identical contour, chamber, twist barrel but 11.5". I have heard of noticable velocity jumps from 10.5" to 11.5". I found it hard to believe but wanted to test it for myself. I was pretty amazed yesterday shooting the identical ammo in both the 10.3" DD upper and 11.5" upper..
I tested my 55VMAX / 25.4gr H4895 load which is extremely accurate in my 10.3" barrel with a velocity of 2560. That same exact ammo shot out of the new 11.5" has a velocity of 2710. Thats a lot bigger jump in velocity than your normal 20fps per inch...... I read had all kinds of stories, but supposedly you get a full powder burn with the 11.5". IDK but those numbers dont lie over the Labradar yesterday...
To add some more data, PMC X-Tac 62gr M855 out of the 11.5" 2730fps. I didnt shoot any out of the 10.3"
I tested my 55VMAX / 25.4gr H4895 load which is extremely accurate in my 10.3" barrel with a velocity of 2560. That same exact ammo shot out of the new 11.5" has a velocity of 2710. Thats a lot bigger jump in velocity than your normal 20fps per inch...... I read had all kinds of stories, but supposedly you get a full powder burn with the 11.5". IDK but those numbers dont lie over the Labradar yesterday...
To add some more data, PMC X-Tac 62gr M855 out of the 11.5" 2730fps. I didnt shoot any out of the 10.3"
Last edited:
Here’s my 10.5in Seekins with their toolless adjustable block. Cats ass
Differences between barrels
10.5" total propellant burnt 62gr SS109/M855 H335/wc844 powder 92.7%, total bullet time in barrel .000625 seconds
11.5" --------------------------------------------------------------------------93.9%-------------------------------------.000657 seconds a difference in dwell time of .000032 seconds.
12.5" barrel -----------------------------------------------------------------94.9%
16" barrel--------------------------------------------------------------------97.1%
20" barrel-------------------------------------------------------------------98.5%
10.5" total propellant burnt 62gr SS109/M855 H335/wc844 powder 92.7%, total bullet time in barrel .000625 seconds
11.5" --------------------------------------------------------------------------93.9%-------------------------------------.000657 seconds a difference in dwell time of .000032 seconds.
12.5" barrel -----------------------------------------------------------------94.9%
16" barrel--------------------------------------------------------------------97.1%
20" barrel-------------------------------------------------------------------98.5%
Last edited:
Since both the 10.5 and 11.5 " barrels use a carbine length gas system and the port is in the same location both have the exact same port pressure, the only difference is .000032 seconds of dwell time. That is 3 /100000 of a second.
[Edit: since I missed the part where you said it's all the exact same, but leaving the info for others]
If you're saying the chamber was cut the exact same (I am not doubting you) and all of the other stuff is the same - then I'm very surprised. I've not had the same experience, but that's not to say it can't happen - I just don't know why it would controlling for all those variables. I'd still work up new loads, you'll probably get close to the same velocity before you show pressure signs. Have you seen the same behavior in heavier loads like 77gr? That's all I've personally tested since I never shoot the lighter stuff.
Last edited:
Similar threads
