Short Barrel AR-15 - Cycle issues.

[rbeckwith]

I have been having issues with a 10.5 inch barreled upper that I bought pre-assembled and cannot figure out what the issue is. Spoke to someone who suggested that it is an issue of the short barrel and the lack of pressure. He suggested that I put on a muzzle break instead of a flash hider and said that would give me more back pressure and should help to cycle the bolt more reliably.

Anyone here have a similar experience and care to weigh in?

 

[Eagle1899]

Re: Short Barrel AR-15 - Cycle issues.

Did you contact the builder? Could be one of a few things.

 

[Joe Curnarski]

Re: Short Barrel AR-15 - Cycle issues.

You don't indicate what specific "issues" you are having. That being said, first I would contact the manufacturer of the upper.

"Issues" might be related to the everything from faulty magazine(s),action(buffer)spring, buffer weight(i.e. H vs H2), leak in the gas system, gas rings, not to mention, proper lubrication.

It is my understanding that SBRs less than 11.5" can be finicky. However I run a 10.5 inch Noveske CQB as my patrol/team rifle with no problems whatsoever.

I hope that someone more knowledgeable may chime in and help. You may want to be specific as to what issues you are having with the upper.

Good luck,

Joe

 

[normbal]

Re: Short Barrel AR-15 - Cycle issues.

Had a bushmaster/essential arms M16 around 1997-2002 that wouldn't cycle with the shorter barrel. Tried a "pigtail" (coiled gas tube), heavier buffer (don't recall the maker, but it was some kind of sliding tungsten piece on an extension to the buffer that would slam the bolt home), stiffer wolff spring, drilling the gas port. Not in that order.

Had a former SF armorer play with it for about 3 months, he found It would ONLY run with OEM federal ammunition (which was about 25 cents/round at the time) OR a 16" or longer upper. Couldn't get it to run on any other ammo. Russian, milsurp, home-brewed mil spec, nothing. Eventually sold it. Doubled my money.

Try asking around on AR15.com, it's a common problem.

Lots of potential solutions.

 

[GlockandRoll]

Re: Short Barrel AR-15 - Cycle issues.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: normbal</div><div class="ubbcode-body">Had a bushmaster/essential arms M16 around 1997-2002 that wouldn't cycle with the shorter barrel. Tried a "pigtail" (coiled gas tube), heavier buffer (don't recall the maker, but it was some kind of sliding tungsten piece on an extension to the buffer that would slam the bolt home), stiffer wolff spring, drilling the gas port. Not in that order.

Had a former SF armorer play with it for about 3 months, he found It would ONLY run with OEM federal ammunition (which was about 25 cents/round at the time) OR a 16" or longer upper. Couldn't get it to run on any other ammo. Russian, milsurp, home-brewed mil spec, nothing. Eventually sold it. Doubled my money.

Try asking around on AR15.com, it's a common problem.

Lots of potential solutions.</div></div>

+1 to all of this.
Timing is the main issue in most of my experiences.. an adjustable gas-block and heavier buffer should help. I'd just go to a gas-piston system if I needed that short of a BBL.

I've gotten one of mine to work, but it's got a TAC-16 welded onto the end an an adjustable fulton-armory tube I cut to carbine/pistol lenght.

 

[jakhamr81]

Re: Short Barrel AR-15 - Cycle issues.

You defiantly need to give us more info. What is the problem? What ammo are you shooting? What buffer weight do you have? What gas block do you have? The more info the better someone can diagnose your problem.

 

[rbeckwith]

Re: Short Barrel AR-15 - Cycle issues.

This is the very first AR that I have ever built, and I put it together from parts that I bought here and there. The upper that I bought was already assembled and complete. I will have to get with the person who I bought the upper from and see what I can find out about it.

I will post the details as soon as I have them.

 

[rbeckwith]

Re: Short Barrel AR-15 - Cycle issues.

What can I say....I am not an AR Guy. This is the first one that I have ever owned.

 

[MD2Colo]

Re: Short Barrel AR-15 - Cycle issues.

Shotgun maintenance sucks, especially with expensive stuff but try an H2 buffer and spring...cheap and idiot-proof.
Solved problems on SBR uppers for two of my buddies, one has a PWS 7" Diablo that was stovepiping and not feeding properly. The other was a 10.5" chopped Colt HBAR.
$.02

-edit
this is with M855 and M855A1 ammo, fwiw

 

[sweetbeard]

Re: Short Barrel AR-15 - Cycle issues.

My 10inch would cycle reliably without a suppressor for the first 2-300 rnds..

after that I got broke in real good and now runs fine without a suppressor.

try good ammo and a lighter buffer tube.

 

[rbeckwith]

Re: Short Barrel AR-15 - Cycle issues.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MD2Colo</div><div class="ubbcode-body">Shotgun maintenance sucks, especially with expensive stuff but try an H2 buffer and spring...cheap and idiot-proof.
Solved problems on SBR uppers for two of my buddies, one has a PWS 7" Diablo that was stovepiping and not feeding properly. The other was a 10.5" chopped Colt HBAR.
$.02

-edit
this is with M855 and M855A1 ammo, fwiw </div></div>

This sounds a lot like what I am experiencing...feeding problems and stove pipes. My magazines are all Colt mags with the green followers, which as I understand are supposed to be decent magazines. This rifle, with the exception of the lower is made up of mil-spec parts. I think this barrel is a Shaw chromoly, but not sure. I have tried several different ammo makers and have experienced the same mis feeds and jams.

 

[Ragnarok]

Re: Short Barrel AR-15 - Cycle issues.

had the same problems with mine, it would get stuck with a spent casing in the chamber as well as it tried to push in a new round.

i orderd a extra hard rifle spring, one spikes heavy buffer, and extra hard extractor spring.

problem solved. i have fired hundres of rounds after this without any issues.

 

[rbeckwith]

Re: Short Barrel AR-15 - Cycle issues.

I can post some photos if y'all think that it will help me to diagnose the issue. I am going to start with the buffer and spring and see what that does as the piston systems are really expensive....but I am sure it would fix my feeding problems.

 

[Ragnarok]

Re: Short Barrel AR-15 - Cycle issues.

the first thing i would do is to know what kind of stoppage you ve got. i had the issue of to much gas pressure. so the original extractor would slip over the rim of the spendt casing.

i had to slow down the bolt cycling, it was goin to fast.
if you have the same problem you can fix this by ordering a spike ST-T2 buffer, David Tubbs Tubb Precision AR-15 CS Buffer Spring, and a extra power extraction spring with insert.

 

[rbeckwith]

Re: Short Barrel AR-15 - Cycle issues.

Thanks for all the advice guys! I am going to start with a new buffer tube/spring and a stronger spring on my extractor.