your thoughts on an ar short stroking

[UncleDano]

Sounds like you answered the question yourself, with the last line of your post:

"i have another lower with an a2 stock and the 22 arc runs just fine on it, it has a rifle buffer weight."

So, just use the same weight buffer as in your A2 stock.

 

[sneedb82]

Sounds like you answered the question yourself, with the last line of your post:

"i have another lower with an a2 stock and the 22 arc runs just fine on it, it has a rifle buffer weight."

So, just use the same weight buffer as in your A2 stock.

The problem with that logic is that the system as a whole is different using the A2 Stock than with a carbine stock set up. The A2 stock sits in an extension tube that is longer than the carbine style extension tube; the spring used for rifle extension tubes and buffers is a different tension and length than the carbine spring will be. The longer buffer A2 requires a longer spring, since the travel in the A2 extension tube is further from the action on the AR15 style platform.

As far as recoil management, the Standard tension in the rifle spring will be equivalent force wise to that of the standard carbine spring. So while he mentioned using an A2 length buffer, tube, and spring worked, all he affirmed is that the STANDARD recoil management system worked. My commentary above referenced the same thing, just in the Carbine set up. Using the adjustable LOP set up of a carbine extension, use the standard carbine spring and carbine buffer and it will be the equivalent of the A2 set up he mentioned. Problem solved.

 

[SSG Graybush]

One last time.
OP are you using a rifle buffer and/or rifle spring in a carbine/collapsible stock?
If so thats your problem. Count the spring coils, 41-42 coils is a rifle spring and 37-39 is a carbine spring. Just those extra coils will cause the short stroke/inability to pick up rounds.
I've seen this situation a few times at the range with inexperienced AR builders.

 

[[email protected]]

i have an ar with a Faxon 16" gunner match barrel, it has a rifle length gas system. i have a 6mm arc as well and it functions just fine , i took the lower off the 6mm and put it on the 22. it has a carbine length tube with collapsable stock. the rifle is a single shot, eject the spent shell but does not pick up the next shell. i pulled the buffer weight and spring, it has a red springco extra heavy duty spring and a h1 weight. i have another lower with an a2 stock and the 22 arc runs just fine on it, it has a rifle buffer weight. (6")

any suggestions? thinking of replacing the red spring with a aero mill spec to see if it will run.

 

[[email protected]]

Had a similar issue when building Rifle length gas tube AR10. Found diagram chart showing ejection angle and suggestions to help resolve short stroking and overgassed ejection. Changed buffers. Even placed a J P adjustable gas block. That didn't totally resolve short stroking. Finally got the gas port enlarged. Bingo that resolved ejection issues. Definitely discovered building AR10 is different from AR15. Especially when home building them was new in 2015. Good luck and have patience. This too will pass.

 

[UncleDano]

The problem with that logic is that the system as a whole is different using the A2 Stock than with a carbine stock set up. The A2 stock sits in an extension tube that is longer than the carbine style extension tube; the spring used for rifle extension tubes and buffers is a different tension and length than the carbine spring will be. The longer buffer A2 requires a longer spring, since the travel in the A2 extension tube is further from the action on the AR15 style platform.

As far as recoil management, the Standard tension in the rifle spring will be equivalent force wise to that of the standard carbine spring. So while he mentioned using an A2 length buffer, tube, and spring worked, all he affirmed is that the STANDARD recoil management system worked. My commentary above referenced the same thing, just in the Carbine set up. Using the adjustable LOP set up of a carbine extension, use the standard carbine spring and carbine buffer and it will be the equivalent of the A2 set up he mentioned. Problem solved.

I think you are missing the fact that the carb buffer is about 3 oz. while the A2 buffer is about 5.5 oz.. So, no, the carb spring & buffer will NOT be the equivalent of the A2 set up.

 

[Roughrice]

HMMMM...
Well... The correction of the issue has been addressed many times by now.
Half of you are right on and the other half...well, Not so sure! LMAO!!
Perhaps someone will chime in who the OP actually listens to.

If OP would keep up with posts of what's recommended to do and report back to what has actually been tried would help greatly!

Been there, done that.

Good Luck!
I'm out!

 

[UncleDano]

HMMMM...
Well... The correction of the issue has been addressed many times by now.
Half of you are right on and the other half...well, Not so sure! LMAO!!
Perhaps someone will chime in who the OP actually listens to.

If OP would keep up with posts of what's recommended to do and report back to what has actually been tried would help greatly!

Been there, done that.

Good Luck!
I'm out!

Just to add the correction of the issue that has been addressed many times now:

A 16" barrel with a rifle length gas tube length is a poor combination and will give you an extremely short dwell time. And as mentioned by others will be tricky to tune.

It is possible that you need a little more delay before unlock to increase dwell time by a few milliseconds.
If that is the case, what others have been suggesting: lighter spring, lighter buffer, is just the opposite of what you need to do.
Increasing the spring tension or increasing the buffer weight will help delay before unlock.
So, sometimes the fix is counter intuitive. But the short barrel and long gas tube gives you a big clue.

Had this similar problem with my AR-10. 18" Barrel, rifle gas system. Rifle was tuned and shooting perfectly. I put in a Wilson Combat "low mass" bolt carrier, and the bolt would not lock back. Put the original heavier bolt back in, and it functions fine. It was just a small 3.05 oz. difference but it made the difference between function and fail.

 

[foxhunter]

that makes sense, the rifle is ejecting fine with a throw of 4:00 but does not lock open on the last shot.

 

[UncleDano]

that makes sense, the rifle is ejecting fine with a throw of 4:00 but does not lock open on the last shot.

Yes, Get an H3 or heavier buffer and give it a try. Report back.

 

[sneedb82]

that makes sense, the rifle is ejecting fine with a throw of 4:00 but does not lock open on the last shot.

If you're ejecting at around 4, you're short stroking, also known as "not getting enough gas". This would be counter productive to add weight to your buffer or increase the buffer weight. You're not getting enough gas to your bolt carrier for it to lock up, but enough is coming in to eject and cycle the next round.

Two things:
- Turn your adjustable gas block to the fully open position shoot with it that way; see if there's soot/carbon build up after shooting to see if you're getting gas leakage.
- If no gas leakage, then make certain that you're using the correct Buffer Spring (coil counting if necessary, but measure total length uncompressed) and Carbine Buffer.

If you're still using the A2 Buffer, spring and Tube, then that could mean that you are using the right component, just getting some gas leakage from you gas block, or at the gas key on your carrier. Look for leakage there as well. If all seems to be good and no carbon signs on the gas system components, then your port on the barrel just needs to be broken in some with more shooting. If you feel confident in opening the gas port yourself, you could do that as a last resort, but I strongly recommend you have a gunsmith or Faxon handle that for you instead.

 

[UncleDano]

If you're ejecting at around 4, you're short stroking, also known as "not getting enough gas". This would be counter productive to add weight to your buffer or increase the buffer weight. You're not getting enough gas to your bolt carrier for it to lock up, but enough is coming in to eject and cycle the next round.

Two things:
- Turn your adjustable gas block to the fully open position shoot with it that way; see if there's soot/carbon build up after shooting to see if you're getting gas leakage.
- If no gas leakage, then make certain that you're using the correct Buffer Spring (coil counting if necessary, but measure total length uncompressed) and Carbine Buffer.

If you're still using the A2 Buffer, spring and Tube, then that could mean that you are using the right component, just getting some gas leakage from you gas block, or at the gas key on your carrier. Look for leakage there as well. If all seems to be good and no carbon signs on the gas system components, then your port on the barrel just needs to be broken in some with more shooting. If you feel confident in opening the gas port yourself, you could do that as a last resort, but I strongly recommend you have a gunsmith or Faxon handle that for you instead.

Sorry, but short stroking is not only related to not getting enough gas! If it is ejecting at 4:00 o'clock, he is not under gassed, but just right. He did not say he was using an AGB. I agree he could consult Faxon. Let him report back on the heavy buffer use.

 

[sneedb82]

Sorry, but short stroking is not only related to not getting enough gas! If it is ejecting at 4:00 o'clock, he is not under gassed, but just right. He did not say he was using an AGB. I agree he could consult Faxon. Let him report back on the heavy buffer use.

He referenced that it would be next, so that is why I mentioned it. But yes, it's slightly undergassed still as has been discussed ad nauseum, and honestly, I'd just keep shooting it if it's cycling but not locking up. I'm pretty sure it's leaking at the gas block.

 

[UncleDano]

He referenced that it would be next, so that is why I mentioned it. But yes, it's slightly undergassed still as has been discussed ad nauseum, and honestly, I'd just keep shooting it if it's cycling but not locking up. I'm pretty sure it's leaking at the gas block.

If it is under gassed and leaking at the gas block, then why does it perform perfectly with the A2 stock (w/heavy buf) installed?