Help with AR10 weird cycling issue

[Bevo]

Gun is as follows:

• Mega receiver set
• Seekins .308 16" barrel
• SLR AGB
• JP HP bolt in a Ballistic Advantage carrier
• Slash Heavy Buffer w/ recommended spring for A5 buffer tube
• Geissele SSA-E
• Suppressed

I have shot it in this configuration numerous times, including many hunts, with no problem. However, it was not behaving last time out.

The gun would cycle, pick up the next round, and appear to close the bolt all the way, but then click - no bang. It would allow me to fire the next round if I pulled the charging handle enough to pass the bolt back over the trigger and reset it, then let it fly back into chamber. Sometimes next round was fine, sometimes I'd get 3 in a row where I'd just get a click when pulling the trigger. It also didn't fire when dropping the bolt on a new mag a couple times.

Gun is relatively clean, not gunked up or anything. Happened with two different factory loads and my hand loads. What say you Hide?

 

[Edsel]

Is this a possibility?

 

[Makinchips208]

Sure its all the way in battery?

Does the click when it doesnt fire seem different than the good click when it would fire?

Couple weeks ago a friends ar would randomly click, leave a tiny mark on the primer, but not fire. Swapped several things around, then found the hammer was falling to almost like a half cocked. It was a drop in trigger that was faulty.
I dont know if the SSA-E would do that or not.

 

[Ernest 5.56]

Inspect the bolt face and firing pin

What do your primers look like?

 

[PhrogDriver]

Could it be bolt bounce? Maybe check the gas rings. The bolt might be going into battery then bouncing rearward, coming slightly out of battery, so the firing pin wasn't consistently striking the primer. Happened to me, and my gas rings weren't holding the bolt. A few dollars worth of new gas rings did the trick.

 

[Ernest 5.56]

People have had trouble with the single piece gas rings

 

[BenE]

Factory or handloads?

 

[Bevo]

View attachment 8673561

Is this a possibility?

No, but I’m going to pull the trigger and inspect everything.

 

[Bevo]

Inspect the bolt face and firing pin

What do your primers look like?

This was my first guess. Bolt face looked fine but I’m going to pull it, clean it, and take a closer look. Primers look normal.

 

[Edsel]

If it’s that dirty, maybe it’s just accumulated brass fragments in the firing pin channel, or something like that.

 

[stanley_white]

I gotta ask, does your rifle have a forward assist?

-Stan

 

[Bevo]

I gotta ask, does your rifle have a forward assist?

-Stan

Nope.

 

[bfoosh006]

Check to make sure you don't have a primer "disc" in the firing pin channel , from a pierced primer.

 

[nagantguy]

My first guesses folks above have already guessed but to reinforce- shit, brass piece of old primer in the FP channel and the JP one piece gas rings are great I hear except when they don’t work .

 

[mudholestomper]

If it’s that dirty, maybe it’s just accumulated brass fragments in the firing pin channel, or something like that.

That’s my guess. I haven’t had it happen on any of my 556 guns, but there’s violence going on inside the upper of my 308 gas gun, and I’ve had a brass shaving limit my firing pin motion.

I’ve had nothing but great experience with the JP one piece gas rings. I love the way they smooth out the cycling. I’ve got a JP bolt in my AR10 and one of my AR15s. No issues whatsoever.

 

[Bevo]

I pulled it apart and don't see any issues.

Based on info here and some back and forth with Chat-GPT, my guess is gas rings. Will replace and see if it fixes anything.

 

[TonyAngel]

Although it sounds like you're having a problem with the bolt not going into battery, with the described setup, I doubt that's the problem, if the rig has been running and is only now giving you problems. I also doubt that it's bolt bounce, again due to your setup.

I'm assuming that you're using the buffer appropriate for an A5 tube. If you weren't you'd be having other problems.

Pull your firing pin and inspect the tip. Compare it to a known good firing pin, if you dont know what your looking for. A couple thousandths can be the difference between a bang and a click.

Shoot, firing pins are cheap. Just replace it and see what it gets you.

Also, when you inspected the carrier for blockage, did you clean it? Don't neglect the bolt carrier group. It's what makes things happen.

 

[Bevo]

Replaced the JP one-piece gas ring with Sprinco rings and that solved the issue.

 

[joe777]

How would gas rings fix the issue of not firing when dropping the bolt on a new mag?

 

[TonyAngel]

Replaced the JP one-piece gas ring with Sprinco rings and that solved the issue.

Wow. Ok, unless I missed it, you didn't mention before that you were running a one piece ring. One piece rings don't compress like standard rings do. Although, theoretically, they should give you a better seal, due to tolerance stacking, they can be too tight in some cases. Better isn't always better.

 

[inertia]

The problem wasn't the gas ring just that it wanted more gas or was leaking too much due to parts mismatch. It just needed more gas than was currently set for at the AGB. 1 click would have probably done it. But the jp rings are ment to be in jp carriers and indeed you can end up leaking gas inconsistently and unpredictably when you don't use the matching carrier and put their bolt in a different brands carrier.

 

[TonyAngel]

The problem wasn't the gas ring just that it wanted more gas or was leaking too much due to parts mismatch. It just needed more gas than was currently set for at the AGB. 1 click would have probably done it. But the jp rings are ment to be in jp carriers and indeed you can end up leaking gas inconsistently and unpredictably when you don't use the matching carrier and put their bolt in a different brands carrier.

Sorry, I don't agree with any of this. If there was sufficient gas to extract and eject the spent casing and the bolt went back far enough to peel another round off of the top of the magazine, insufficient gas wasn't the problem.

The one piece rings are intended to be a direct replacement for standard rings in any carrier. Are you saying that JP bolts and carriers will only work with each other?

 

[inertia]

I am saying from real experience not opinion some non jp carriers don't work well with the jp one piece ring and have unpredictable cycling issues just as described. Using traditional rings can fix it but using a jp carrier very likely would also have fixed it. And no just because a case ejects and the bolt catches the rim of the next round doesn't mean it has enough velocity to make it all the way home consistently which is probably exactly what happened here. But hey what do I know I just read about this online I haven't shot these guns much.

Sorry, I don't agree with any of this. If there was sufficient gas to extract and eject the spent casing and the bolt went back far enough to peel another round off of the top of the magazine, insufficient gas wasn't the problem.

The one piece rings are intended to be a direct replacement for standard rings in any carrier. Are you saying that JP bolts and carriers will only work with each other?

 

[GhostFace]

I wonder what the issue is with the JP one piece rings? I’ve been using McFarland one piece rings in my Armalites for 26 years and I’ve never had an issue with them. Maybe they are spec’d differently?

 

[PhrogDriver]

I wonder what the issue is with the JP one piece rings? I’ve been using McFarland one piece rings in my Armalites for 26 years and I’ve never had an issue with them. Maybe they are spec’d differently?

From what I understand, their rings are designed for their bolt, which in turn is designed for their low mass carrier. Because their carrier is lighter than a standard carrier, the gas rings on the bolt don't need to create as much friction to prevent bolt bounce. However, when used with a standard carrier, which has more momentum due to its mass, the rings don't have the friction necessary to prevent bolt bounce.

 

[msgriff]

I wonder what the issue is with the JP one piece rings? I’ve been using McFarland one piece rings in my Armalites for 26 years and I’ve never had an issue with them. Maybe they are spec’d differently?

The JP 1-piece ring is manufactured so that there is a lot less friction between the bolt and the carrier, which freaks a lot of people out who are used to the friction of 3-piece or other McFarland type rings. They are compatible with other DPMS spec bolts and carriers, but I've heard of some rare issues with the width of the bolt ring groove and compatibility between 1-piece and 3-piece rings.

"JP .308 Enhanced Gas Rings

As a replacement for traditional three-piece gas rings, the JPEGR-308 utilizes a one-piece design similar to the McFarland rings. Unlike the McFarland rings, though, our precision-ground gas rings are engineered to precisely suit DPMS-patterned carrier group components such as our own JP EnhancedBolt™.

After testing numerous minute grind callouts, the final JP Enhanced Gas Rings spec is the perfect balance of a solid gas seal with a very low-friction relationship between rings and bolt carrier. Reducing the resistance between these components directly results in an overall increase in the rifle's operational window while the edge of the rings utilizes the cycling action itself to scrape the walls of the carrier, helping shed fouling with every shot.

The JPEGR-308 is not compatible with large-frame Armalite bolt assemblies."