Charging handle snaps back when trigger pulled

Clearwater717 · January 14, 2018, 02:59 PM

I've read through many threads and it seems the issue I am experiencing with my 2012 LWRC A6 Pistol is very rare. Yesterday at Gun Club, when I squeezed the trigger, the charging handle snapped back with the bolt. The catch/hook on the charging handle broke off and the bolt jammed back. I've cleared everything, bolt back in place, etc. I replaced the broken charging handle with a brand new LWRC ambi charging handle. I took it to range again, and it happened again. I didn't fire a second round because I was attempting to avoid catastrophic damage to the weapon. Has anyone else ever experienced this? All my other AR platform rifles are all Sig Sauer and are newer and have never even experienced a feed jam, the LWRC is my oldest rifle. Could be a problem in the trigger box action, maybe old springs? Please help if you have any idea, this one has got me pulling my hair out. Thank you.

**JohnKSa** · January 14, 2018, 03:15 PM

Do NOT fire the gun again until the issue is definitely resolved.

Something is hitting the charging handle when the bolt cycles but that should NEVER happen unless there is a problem in the gun.

stagpanther · January 14, 2018, 03:51 PM

Sounds like you're having an over-pressure situation--but hard to diagnose based on this little info. How did the carrier jam--into the buffer tube? Unless you're absolutely sure you dodn't have a pressure situation I'd go with John's suggestion and cease firing immediately--potentially 50 to 60,000 psi (and maybe more) is a lot of power launching that mass back at your face which is only inches away.

Clearwater717 · January 14, 2018, 04:27 PM

Thank you all for the input and for your concern. Yes, the weapon is
out of commission until I get this resolved. I'm not familiar how to set the pressure for the piston on a 2012 A6 .556 pistol. Any insight what I should be looking for and what setting is proper for non-suppressed shooting? Yep, the charging handle snapped back so hard it snapped off the hook that is supposed to keep it in place....then the charging handle slammed forward and the bolt jammed back partially into the buffer tube. I thought I was seeing things. I've never had this problem with this weapon, ever. Never even had a simple jamming issue with the different variations of the AR platform made by Sig. I may have to take it to a pro.

HiBC · January 14, 2018, 04:46 PM

I'd agree,don't shoot it till you find and fix the problem.
I'm not able to envision how overpressure or overgassing would cause this...at least not in the cartoons I watch in my head.
The op rod is not part of the gas system.
Working properly,there should not be significant contact between the BCG and the op rod in firing.

I'm mental blocking the proper name of the doohickey that screws on top of the BCG and telescopes over the gas tube.The one that gets "Properly staked"

I have seen the staking on a new BCG bulge out the sides of the "doohickey",increasing its width,and causing interference with the op rod.
A few file strokes took the high spot off.
I suppose if the screws/staking failed,and proper doohickey alignment was lost,there could be doohickey/op rod interference.

But in any case,I'd say you have a problem with your doohickey.

burrhead · January 14, 2018, 04:52 PM

Carrier key

HiBC · January 14, 2018, 04:54 PM

Thank you!

stagpanther · January 14, 2018, 04:54 PM

Ahh--didn't notice at first piston gas pistol--no experience with that, but it doesn't sound good. At the very least call the manufacturer--I'm sure they will be happy to help you solve your issue.

HiBC · January 14, 2018, 05:01 PM

Piston??
Hmmm. I don't know about those.
Still,All the op rod is supposed to do is pull the BCG back.Other than that,the BCG ,piston,etc,I believe,should run within the op rod with no interference.

You have another part in the place of the direct impingement gas key,that the piston contacts,I assume. A doohickey.

Either the doohickey or the piston is somehow becoming misaligned
You might look to the hole in the upper the piston passes through,or the holes in the barrel nut.
And,odds are good the latch feature in your upper,where the op rod catch engages,is hosed.

See if the manufacturer will take it.You probably need an upper receiver for that reason alone.

ed308 · January 14, 2018, 10:26 PM

Not heard about this problem before now. Is a part of the bolt is hitting the charging handle as it cycles? Odd problem. Call LWRC's technical support. And let us know what they say.

For those who don't know how LWRC's piston system works, they don't have a carrier key like DI ARs. At least not newer LWRC piston ARs like I have. Gas is vented at the front of the hand guard instead of in the upper receiver. The carrier key is usually a machined part of the bolt carrier and solid except for a cup where the piston rod seats. The system works by gas forcing the piston rod back which then pushes the bolt back which cycles the AR. Simple and effective system.

ed308 · January 14, 2018, 11:05 PM

Another thought, check the piston system and make sure it was assembled correctly and working as it should.

Bartholomew Roberts · January 15, 2018, 07:40 AM

Well, either the piston is striking the front of the charging handle or the carrier is striking the charging handle as it travels back. Do you have an estimate of how many rounds through the pistol? Do you notice any wear markings in the rear of the upper receiver or the fat ring at the end of the carrier?

Clearwater717 · January 15, 2018, 03:04 PM

I will call LWR and see what they have to say. I will post what they recommended.

Clearwater717 · January 15, 2018, 03:42 PM

LWRC said it was no doubt one issue. The buffer installed is too long or too short. He explained "the bolt needs more space to cycle back". He said all LWRC AR platform guns use a "H2" size buffer. He recommended I contact SB Tactical and ask them what size buffer they recommend for a short barrel AR. I sent them an email, no contact yet. But the gentlemen at LWRC said he is 100% sure that is the issue. He's seen it happen many times.

stagpanther · January 15, 2018, 03:56 PM

Quote:

The buffer installed is too long or too short.

That's exactly what I would have said--but I didn't know if their particular system needed the buffer and spring like a conventional DI pistol or AR. Are you sure at some point along the way you didn't switch the buffer/spring with another system's?

ed308 · January 15, 2018, 08:01 PM

They do use the H2 buffer. Glad they could help.

HiBC · January 15, 2018, 08:29 PM

If LWRC says so,I'm willing to accept they know more about it than I do.

Now I am curious,though.

I don't understand any contact between the buffer and the op rod.....

UNLESS..??? its about the length of the buffer?As the BCG travel stop? I suppose if the BCG recoils too far,the "gas key" or whatever dorsal projection exists on the BCG could smack the rear of the op rod with violence.

Are there different buffer tube lengths for the AR pistols? Tube length could play a part.

Clearwater717 · January 15, 2018, 09:48 PM

Apparently, LWRC has a proprietary buffer spring and buffer that is only used on the M6-A2 .556 Piston Pistol. The spring is quite a bit shorter, as well as the buffer itself, and the letters/numbers "R2" are stamped on it. It works perfectly if you don't change the length of the buffer tube. The brace I installed made by SB Tactical has a slightly longer buffer tube. BTW, nothing in the instruction manual for install said it needed to have a true carbine H2 buffer and spring. Scottsdale Gun Club hooked me up, I installed the new buffer and spring in about 1 minute, and now the gun runs like a sewing machine. I put 9 mags through it of .556, no jams, nothing, ran flawless. The guy at LWRC mentioned this error has created a very serious problem that could end very badly for the weapon and the operator. Serious stuff.

Clearwater717 · January 15, 2018, 10:15 PM

Oddly enough, no. I just assumed the damn spring and buffer was H2, as I did notice the spring was shorter. But you were right, the hardest working part of the gun was the issue, the buffer and buffer spring. Thank you for your insight.

January 14, 2018, 02:59 PM	#1
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	Charging handle snaps back when trigger pulled I've read through many threads and it seems the issue I am experiencing with my 2012 LWRC A6 Pistol is very rare. Yesterday at Gun Club, when I squeezed the trigger, the charging handle snapped back with the bolt. The catch/hook on the charging handle broke off and the bolt jammed back. I've cleared everything, bolt back in place, etc. I replaced the broken charging handle with a brand new LWRC ambi charging handle. I took it to range again, and it happened again. I didn't fire a second round because I was attempting to avoid catastrophic damage to the weapon. Has anyone else ever experienced this? All my other AR platform rifles are all Sig Sauer and are newer and have never even experienced a feed jam, the LWRC is my oldest rifle. Could be a problem in the trigger box action, maybe old springs? Please help if you have any idea, this one has got me pulling my hair out. Thank you.

January 14, 2018, 03:15 PM	#2
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,992	Do NOT fire the gun again until the issue is definitely resolved. Something is hitting the charging handle when the bolt cycles but that should NEVER happen unless there is a problem in the gun. __________________ Do you know about the TEXAS State Rifle Association?

January 14, 2018, 03:51 PM	#3
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	Sounds like you're having an over-pressure situation--but hard to diagnose based on this little info. How did the carrier jam--into the buffer tube? Unless you're absolutely sure you dodn't have a pressure situation I'd go with John's suggestion and cease firing immediately--potentially 50 to 60,000 psi (and maybe more) is a lot of power launching that mass back at your face which is only inches away. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

January 14, 2018, 04:52 PM	#6
burrhead Senior Member Join Date: July 6, 1999 Location: Chihuahuan desert, Texas Posts: 1,148	Carrier key __________________ Join the GOA, SAF and the TSRA I'm offended by people that are easily offended.

January 14, 2018, 04:54 PM	#8
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,789	Ahh--didn't notice at first piston gas pistol--no experience with that, but it doesn't sound good. At the very least call the manufacturer--I'm sure they will be happy to help you solve your issue. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

January 14, 2018, 04:27 PM	#4
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	Thank you all for the input and for your concern. Yes, the weapon is out of commission until I get this resolved. I'm not familiar how to set the pressure for the piston on a 2012 A6 .556 pistol. Any insight what I should be looking for and what setting is proper for non-suppressed shooting? Yep, the charging handle snapped back so hard it snapped off the hook that is supposed to keep it in place....then the charging handle slammed forward and the bolt jammed back partially into the buffer tube. I thought I was seeing things. I've never had this problem with this weapon, ever. Never even had a simple jamming issue with the different variations of the AR platform made by Sig. I may have to take it to a pro.

January 14, 2018, 04:46 PM	#5
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	I'd agree,don't shoot it till you find and fix the problem. I'm not able to envision how overpressure or overgassing would cause this...at least not in the cartoons I watch in my head. The op rod is not part of the gas system. Working properly,there should not be significant contact between the BCG and the op rod in firing. I'm mental blocking the proper name of the doohickey that screws on top of the BCG and telescopes over the gas tube.The one that gets "Properly staked" I have seen the staking on a new BCG bulge out the sides of the "doohickey",increasing its width,and causing interference with the op rod. A few file strokes took the high spot off. I suppose if the screws/staking failed,and proper doohickey alignment was lost,there could be doohickey/op rod interference. But in any case,I'd say you have a problem with your doohickey.

January 14, 2018, 05:01 PM	#9
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	Piston?? Hmmm. I don't know about those. Still,All the op rod is supposed to do is pull the BCG back.Other than that,the BCG ,piston,etc,I believe,should run within the op rod with no interference. You have another part in the place of the direct impingement gas key,that the piston contacts,I assume. A doohickey. Either the doohickey or the piston is somehow becoming misaligned You might look to the hole in the upper the piston passes through,or the holes in the barrel nut. And,odds are good the latch feature in your upper,where the op rod catch engages,is hosed. See if the manufacturer will take it.You probably need an upper receiver for that reason alone. Last edited by HiBC; January 14, 2018 at 05:20 PM.

January 14, 2018, 10:26 PM	#10
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	Not heard about this problem before now. Is a part of the bolt is hitting the charging handle as it cycles? Odd problem. Call LWRC's technical support. And let us know what they say. For those who don't know how LWRC's piston system works, they don't have a carrier key like DI ARs. At least not newer LWRC piston ARs like I have. Gas is vented at the front of the hand guard instead of in the upper receiver. The carrier key is usually a machined part of the bolt carrier and solid except for a cup where the piston rod seats. The system works by gas forcing the piston rod back which then pushes the bolt back which cycles the AR. Simple and effective system. Last edited by ed308; January 14, 2018 at 11:01 PM.

January 14, 2018, 11:05 PM	#11
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	Another thought, check the piston system and make sure it was assembled correctly and working as it should.

January 15, 2018, 07:40 AM	#12
Bartholomew Roberts member Join Date: June 12, 2000 Location: Texas and Oklahoma area Posts: 8,462	Well, either the piston is striking the front of the charging handle or the carrier is striking the charging handle as it travels back. Do you have an estimate of how many rounds through the pistol? Do you notice any wear markings in the rear of the upper receiver or the fat ring at the end of the carrier?

January 15, 2018, 03:04 PM	#13
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	I will call LWR and see what they have to say. I will post what they recommended.

January 15, 2018, 03:42 PM	#14
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	LWRC said it was no doubt one issue. The buffer installed is too long or too short. He explained "the bolt needs more space to cycle back". He said all LWRC AR platform guns use a "H2" size buffer. He recommended I contact SB Tactical and ask them what size buffer they recommend for a short barrel AR. I sent them an email, no contact yet. But the gentlemen at LWRC said he is 100% sure that is the issue. He's seen it happen many times.

January 15, 2018, 08:01 PM	#16
ed308 Senior Member Join Date: November 5, 2016 Location: DFW, TX Posts: 1,147	They do use the H2 buffer. Glad they could help.

January 15, 2018, 08:29 PM	#17
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,288	If LWRC says so,I'm willing to accept they know more about it than I do. Now I am curious,though. I don't understand any contact between the buffer and the op rod..... UNLESS..??? its about the length of the buffer?As the BCG travel stop? I suppose if the BCG recoils too far,the "gas key" or whatever dorsal projection exists on the BCG could smack the rear of the op rod with violence. Are there different buffer tube lengths for the AR pistols? Tube length could play a part.

January 15, 2018, 09:48 PM	#18
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	Problem resolved Apparently, LWRC has a proprietary buffer spring and buffer that is only used on the M6-A2 .556 Piston Pistol. The spring is quite a bit shorter, as well as the buffer itself, and the letters/numbers "R2" are stamped on it. It works perfectly if you don't change the length of the buffer tube. The brace I installed made by SB Tactical has a slightly longer buffer tube. BTW, nothing in the instruction manual for install said it needed to have a true carbine H2 buffer and spring. Scottsdale Gun Club hooked me up, I installed the new buffer and spring in about 1 minute, and now the gun runs like a sewing machine. I put 9 mags through it of .556, no jams, nothing, ran flawless. The guy at LWRC mentioned this error has created a very serious problem that could end very badly for the weapon and the operator. Serious stuff.

January 15, 2018, 10:15 PM	#19
Clearwater717 Junior Member Join Date: January 2, 2018 Location: Scottsdale, AZ Posts: 6	Oddly enough, no. I just assumed the damn spring and buffer was H2, as I did notice the spring was shorter. But you were right, the hardest working part of the gun was the issue, the buffer and buffer spring. Thank you for your insight.