How did this happen?

[btq96r]

So, I've been having some issues with my 16" AR recently.  Basically a mix of failure to eject, failure to cycle properly, and failure to lock back after the last round of a mag.  I tried 55gr, 62gr, 20rd mags, 30rd mags, carbine buffer, an H2 buffer at the range to troubleshoot it...and nothing.  Today while cleaning it, the bolt caught my eye, and I think I found the problem.

 

So, for those who see distressed AR's more than me, how the hell did this happen?  It came new with a BCG in a PSA upper last year, and somewhere between 500-1000 rounds through it (I don't keep round counts, just a wide estimate).  This seems way too soon for something like this.

 

 

[Garufa]

One of your gas rings appears to be uh, lacking.  Buy some new ones and replace them.

[Oh Shoot]

One of the three gas rings definitely has a section just gone. Obviously rings should last a lot longer, but stuff happens, bad batch or whatever.

 

But it should run fine with two rings, most of the time even with one, so that may not be the root of your prob.

 

- OS

[btq96r]

I already ordered a four pack of replacement rings off of Amazon for like ten bucks.  Figure I'll swap the current rings with a set and see what happens.  My next step after that is to replace the gas block and tube.

 

Just a bit disappointed that it happened so fast.  Maybe because I've used this BCG in both the 16" and my SBR before I bought a Spikes BCG for my SBR?

 

OhShoot...the problems are off and on.  What I've found is the more I'm shooting that day at the range, the worse it gets. 

Edited January 1, 2016 by btq96r

[Oh Shoot]

....

 

OhShoot...the problems are off and on.  What I've found is the more I'm shooting that day at the range, the worse it gets. 

 

Well, can't think of an obvious "progressive problem" cause right off -- but starting at the basics, if bolt isn't locking back, it's almost certainly due to inadequate gassing for whichever reason, and of course a heavier buffer would be the last thing that could help.

 

Is gas key still good and tight?

 

- OS

 

edit: you mentioned replacing block?  Is it moving around or something? What kind of block, pinned A2 or set screw/bolt on?  Did this rifle run fine previously with this or another BCG?

Edited January 1, 2016 by Oh Shoot

[btq96r]

Well, can't think of an obvious "progressive problem" cause right off -- but starting at the basics, if bolt isn't locking back, it's almost certainly due to inadequate gassing for whichever reason, and of course a heavier buffer would be the last thing that could help.

 

Is gas key still good and tight?

 

- OS

 

edit: you mentioned replacing block?  Is it moving around or something? What kind of block, pinned A2 or set screw/bolt on?  Did this rifle run fine previously with this or another BCG?

 

Yeah, I had an H2 buffer there, so I tried a carbine buffer and no joy.  This is the only BCG it's had in it, and it's run fine until recently.  Gas key is still good, and this is the upper I had the pinned on A2 sight/block taken off of.  It was shooting fine for a while, these problems are recent.  Gas block still looks like it's in good position.  So, I'll try the gas rings and see if that works.  Hoping it does.

[Omega]

Yea, try the gas rings and make sure you keep them lubed and the spaces rotated further apart; though you probably rotated them for the pic.  I run my ARs kinda wet unless I'm in a desert environment, seems to run better that way for me.

[btq96r]

Swapped out the gas rings, and it ran a lot better.  But after about the 50-60th round out of 80 total, it started failing to lock back on the last round again.  I did have the H2 buffer in, and was shooting 55gr ammo, so maybe that's it?  Just can't understand why the problem only came up late in the firing and not from the beginning.

[Oh Shoot]

Swapped out the gas rings, and it ran a lot better.  But after about the 50-60th round out of 80 total, it started failing to lock back on the last round again.  I did have the H2 buffer in, and was shooting 55gr ammo, so maybe that's it?  Just can't understand why the problem only came up late in the firing and not from the beginning.

 

That's just too weird, again can't imagine what could cause a progressive problem like that.

 

The new rings didn't get chewed up right away again did they, maybe some sort of machining problem with inside of the carrier or something really unusual?

 

- OS

[Omega]

Swapped out the gas rings, and it ran a lot better.  But after about the 50-60th round out of 80 total, it started failing to lock back on the last round again.  I did have the H2 buffer in, and was shooting 55gr ammo, so maybe that's it?  Just can't understand why the problem only came up late in the firing and not from the beginning.

Are you running it wet and staggering the rings?  What mag are you using and how many rounds are left when it happens?

[btq96r]

That's just too weird, again can't imagine what could cause a progressive problem like that.

 

The new rings didn't get chewed up right away again did they, maybe some sort of machining problem with inside of the carrier or something really unusual?

 

- OS

 

I haven't broken it down yet to check. 

 

Like I said, it ran like a champ for the first 50 rounds, then sometime after that, it started having issues, intermittent at first, then towards the end consistently..  I was firing in five round groups.  Loading five, shooting, making adjustments on the scope, lather rinse repeat.

[btq96r]

Are you running it wet and staggering the rings?  What mag are you using and how many rounds are left when it happens?

 

Not running it wet, and i staggered the rings when I put them on.  I always thought it never mattered if they lined up or not.

 

I'm using a 20rd PMAG, and the main issue is the bolt not locking back after the last round.  About twice out of 80 rounds (all towards the end) it didn't load the next round.  But it wasn't near as bad as before the new gas rings.

[Omega]

Not running it wet, and i staggered the rings when I put them on.  I always thought it never mattered if they lined up or not.

 

I'm using a 20rd PMAG, and the main issue is the bolt not locking back after the last round.  About twice out of 80 rounds (all towards the end) it didn't load the next round.  But it wasn't near as bad as before the new gas rings.

If it's a new weapon, I would run it wet for a bit.  The gas rings seal the gas in the carrier so alternating them helps them do that.  Check other mags if you haven't yet, sometimes the follower does that to ARs, sometimes the lips do it too but that's mostly on steel mags.

[btq96r]

If it's a new weapon, I would run it wet for a bit.  The gas rings seal the gas in the carrier so alternating them helps them do that.  Check other mags if you haven't yet, sometimes the follower does that to ARs, sometimes the lips do it too but that's mostly on steel mags.

 

This upper and bolt aren't new.  I've got close to 1,000rds through it I'd imagine.  Next time I take it out, I'll bring some extra mags, a carbine buffer, and even my other BCG just to see. 

 

Annoying. 

[res308]

This upper and bolt aren't new.  I've got close to 1,000rds through it I'd imagine.  Next time I take it out, I'll bring some extra mags, a carbine buffer, and even my other BCG just to see. 

 

Annoying. 

I had just started to suggest that. I'm interested to see what the problem is here. Next time you take it out to run it, I would shoot until the problem rears its ugly head again, then stop and change out the entire bolt and carrier assembly. In other words, take out the entire bolt and carrier assembly your using, and install a known "good" assembly. See if it runs fine after that. If it does, you might keep using the "good" carrier, but change back to your original bolt and see if it happens again. Maybe it's just me, but that gap in the bolt where the rings ride seems a touch wide to me.

If neither work, have the gas block checked. If I understood right, your gas block has been changed out. I've run into that before, where the block was ever so slightly out of alignment, not really even visible to the naked eye, but it wasn't getting enough gas.  

Just suggesting a process of elimination. All that and a bottle of Tylenol may get you back on track. I hope!

[btq96r]

Maybe it's just me, but that gap in the bolt where the rings ride seems a touch wide to me.

If neither work, have the gas block checked. If I understood right, your gas block has been changed out. I've run into that before, where the block was ever so slightly out of alignment, not really even visible to the naked eye, but it wasn't getting enough gas.  

 

I put on new gas rings, it delayed the problem, but it still crept back up.  I'd like to think that if it was the gas block, it would be a consistent problem from the first rounds, not something that happens later in the shooting.

[res308]

I put on new gas rings, it delayed the problem, but it still crept back up.  I'd like to think that if it was the gas block, it would be a consistent problem from the first rounds, not something that happens later in the shooting.

Honestly that's what I would think as well, but I'm just practicing a little "straw-grasping." I'm hoping it's all just in the bolt itself. Not a whole lot of things more frustrating than a gun that won't run right.

[Gregory_k]

Try the other bcg.
Staggering the rings does not matter as they may move around and a corectly built rifle will function on 1 ring.

[xtriggerman]

There is a "just right" amount of drag a bolt head should have moving in and out of the carrier. The carrier gas expansion cylinder walls can have defects that will create problems with the smallest amount of fouling. I am not an advocate of lubing this problem away since it is more or less a temporary fix. If lubing anything inside an automatic, it should be with a good dry lube. My go to there is Ezox. When a carrier  has its exhaust holes drilled in, many times the ensuing bur that it produces on the cylinder wall never gets completely honed out along with cylinder wall anomalies such as fine grooves that go all the way around the cylinder. These "choppy" cylinder walls have a way of eating gas rings and collecting fouling giving you a stickier and stickier bolt head movement with rounds fired.  

  Also I will mention, rings are not all the same in quality either. Their sealing face should be square and very smooth (not the case with many vendors) . With use, good rings will pick up a near chrome like burnish on their contact face. Its unfortunate their are so many vendors with slipping QC issues but its all about sales. Good Luck! Oddly, Luck has a lot to do with it!

[Caster]

The things are so cheap, you oughta have a few sets laying around.

Not that they need it but I replace the gas rings, cam pin and cotter pin every thousand rounds or so. Less than fifteen bucks...I spill more than beer than that in a years time.

[Pete123]

Nothing wrong here that an SKS wouldn't fix.  :bowrofl:

Edited February 10, 2016 by Pete123

[btq96r]

Nothing wrong here that an SKS wouldn't fix.  :bowrofl:

 

Save for ammo capacity, weight, sights, and not looking near as cool. :P

[Pete123]

Yeah, but the sks has a wood stock and comes with a pig sticker attached......and, you don't have to worry about losing the magazine.

[xtriggerman]

Save for ammo capacity, weight, sights, and not looking near as cool. :P

 

Well, yer right. as far as the weight goes but I think I have all the other issues licked with my custom SKS build that includes multi position adjustable gas, fined barrel, QD but stocks and forends & VZ58 magazines. Just wish the firing pin hole was a bit smaller but so far no issues with it.

[URL=http://s635.photobucket.com/user/xtriggerman/media/Hybrid%20XTM1C/P1050576.jpg.html][/URL]

[LawEnforcementSalesTN]

 Cool, see a little FAL goodness mixed in there ..

 

 

 

Well, yer right. as far as the weight goes but I think I have all the other issues licked with my custom SKS build that includes multi position adjustable gas, fined barrel, QD but stocks and forends & VZ58 magazines. Just wish the firing pin hole was a bit smaller but so far no issues with it.