AR10 won’t cycle suppressed

Tim

Tim

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Maybe I’m having a brain fart, it’s entirely possible.

New AR10, PSA with carbine buffer/spring/extension and mid-length gas.

Cycles just fine unsupressed. Ejects, but does not load, with suppressor.

So, with that limited info, an adjustable block is not likely to solve the problem. I need MORE gas, not less. Right?

Should I try a lighter buffer/spring? If that doesn’t work, am I looking at drilling out the gas port?
 
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Unless there’s so much gas that the bolt comes back forward before the round is in position?

Unlikely...but not impossible.
 
BigWaylon said:
Unless there’s so much gas that the bolt comes back forward before the round is in position?

Unlikely...but not impossible.
Click to expand...

So much gas, the bolt bounces back before the next round lifts?
 
Mike Overlay said:
So much gas, the bolt bounces back before the next round lifts?
Click to expand...
Correct. With the additional backpressure of the can, the bolt moves so fast the next round can’t be grabbed.

Improbable...but not impossible. Buffer or spring change could fix it.

Is the empty brass flying further when shooting suppressed?

What can? Got a different one (less backpressure) to try?
 
Friend has a DPMS SASS. He had to lighten the buffer spring to cycle supersonic ammo suppressed. His won’t cycle subsonic ammo suppressed at all and has to be cycled manually after every shot
 
Thanks for all the feedback so far guys. I'll need to pick this back up in a few weeks when I have some time.

I only ran ~15 rounds through it today. 5 of those were suppressed. I *should* have thought to run a magazine with just 1 round to see if I got LRBHO, but it didn't cross my mind at the time. Was too busy helping the kid bang steel with his .22!

And...the brass just tossed in a bucket.
 
BigWaylon said:
Correct. With the additional backpressure of the can, the bolt moves so fast the next round can’t be grabbed.

Improbable...but not impossible. Buffer or spring change could fix it.

Is the empty brass flying further when shooting suppressed?

What can? Got a different one (less backpressure) to try?
Click to expand...


It's a SiCo Omega. I *could* swap it out for an AAC 7.62SD, but I won't. I finally have that 7.62SD mounted on a rifle (using a strap wrench) that is giving me good accuracy. In my mind, that can may as well be pinned to that barrel. I'll never take it off.
 
I think Bigwaylon is on to it.
My Barnes 300blk did that initially with the omega. When suppressed, it was throwing the brass at about 1:30-2ish forward which indicates it is over gassed and wouldn't pickup the next round. I had to close off the gas some and now it is gtg. Now that it is adjusted, I put out a bucket and they all land in it, but that may be more of an extractor issue. Do you remember where the brass landed?
 
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You've got too much gas. Get an SLR adjustable gas block, adjust it down unsuppressed until it malfunctions, then open it back up two clicks. It should then run reliably in either suppressed or unsuppressed configuration.

Don't change your buffer spring until after the AGB doesn't solve your issue.
 
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Or,

Wrong buffer length. Do this, take out the recoil spring and insert the buffer. Reassemble the rifle and charge to the rear. The bolt will lock back and STAY back. Then tilt the muzzle up and shake the gun. If you hear the buffer bouncing between the end of the buffer tube and your BCG, its a short buffer.

Then go buy a longer one. Or a shorter buffer tube.
 
JBoyette said:
Or,

Wrong buffer length. Do this, take out the recoil spring and insert the buffer. Reassemble the rifle and charge to the rear. The bolt will lock back and STAY back. Then tilt the muzzle up and shake the gun. If you hear the buffer bouncing between the end of the buffer tube and your BCG, its a short buffer.

Then go buy a longer one. Or a shorter buffer tube.
Click to expand...


I get what you're saying about buffer length. I have a drawer full of buffers to try out. But I'm confused about this test. Even fully compressed, the buffer spring will still take up some space. So, is there a way to quantify how much 'bounce' is correct?
 
Tim said:
I get what you're saying about buffer length. I have a drawer full of buffers to try out. But I'm confused about this test. Even fully compressed, the buffer spring will still take up some space. So, is there a way to quantify how much 'bounce' is correct?
Click to expand...

The spring is to be removed for the test. keep in mind the spring is collapsed around the buffer, not under it.

The soft end of the buffer is to allow a "bounce back" if it ever bottoms out in the buffer tube. This is why we need to see how deep the BCG goes in the buffer tube. If the buffer has room to move back and forth on a compressed BCG/Buffer assembly, that's the issue. Over travel.

Try it, see what happens,

Oh to get the BCG from unlocked to locked, place the muzzle down facing the ground and lightly tap the whole rifle on the muzzle. let the kinetic energy and momentum do the work.
 
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JBoyette said:
keep in mind the spring is collapsed around the buffer, not under it.
Click to expand...

this is what wasn't clicking for me. I figured that even compressed, the spring would take up some space beyond the buffer length.
 
Tim said:
this is what wasn't clicking for me. I figured that even compressed, the spring would take up some space beyond the buffer length.
Click to expand...

I ran into the same issue with a DPMS LR-308 long ago. The issue with any SR-25 pattern guns is the 80% parts swap with the Ar-15. This is why the AR-10 is a better design for a agency, AR-10 is AR-10, AR-15 is AR-15 parts. Prevents the cross part spec issue. That you are running into now.

The real issue "might" be the depth of the buffer tube. Not all are extruded to the same shape or depth.
 
Any update on this? Wondered if you did some of the buffer tests John mentioned...or if it’s the gas issue.
 
BigWaylon said:
Any update on this? Wondered if you did some of the buffer tests John mentioned...or if it’s the gas issue.
Click to expand...


Did some reading on another forum (308arforum) and found that recoil system issues are common for the PA10 with carbine length buffer tubes.

The OEM buffer is 3.7 oz and the spring is ~11."

Research tells me it needs a 5.4oz buffer and ~13" spring. My spring length numbers are approximate...

Anyway, I had the both the 5.4oz buffer and the specified spring in my box-o-stuff. So, I have them installed and plan a range trip this weekend to test. If that doesn't solve things, then I'll pick up an adjustable block and play with that next. Luckily, this is going to be a hunting rig primarily, so I'm not in a terrible rush to solve it.
 
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Tim said:
recoil system issues are common for the PA10 with carbine length buffer tubes.
Click to expand...
Yup, can be a Real Challenge.

There is an alternative buffer tube to use and it is 3/4" longer on the inside.
So regular carbine tube is 7" inside and the one I'm supplying a link for is 7 3/4" inside and is used with spring~s 11 to 13 coils , and regular buffer. You'll figure it out. It works, don't ask how I know ,, LoL .

If you use the setup, you have to watch that the BCG does NOT KISS or Slam into the lower.

Supplying two links, one for the longer buffer tube, $23.00 delivered ( sometimes on sale for $20 delivered ) and an adjustable gas block, ($20 delivered).

FWIW

Safe Shooting
UTG TLU002 PRO AR308
https://extreemtactical.com/utg-tlu002-pro-ar308-6-position-mil-spec-extension-tube-black


STEEL ADJUSTABLE Micro 223Rifle Gas Ring Roll Pin .750 HideUnder QuadRail ($20 delivered )

https://www.ebay.com/itm/STEEL-ADJU...s-Ring-Roll-Pin-750-HideUnder-QuadRail/113589 060276?hash=item1a726f82b4:g:eek:LQAAOSwBZBcKaLY:rk:1:pf:1&frcectupt=true
 
Got it out today and all is well with...
- OEM non-adjustable gas block
- replaced buffer with 5.4oz (OEM was 3.7oz)
- replaced with 34 coil/13.75" spring (OEM is ~11")
- Pmag (steel DPMS mags fail to lock in on closed bolt and fail LRBHO)


I got LRBHO suppressed and unsuppressed with 168gr FGMM, failed to get LRBHO on a handload I had worked up for a bolt gun.

I'm gonna call it good.

FWIW, FGMM produced .8" 100yd group suppressed. That's the 18" SS mid-length gas PSA upper.
 
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