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8/15/2010 10:05:22 AM EDT
I took my new sbr build out to put a couple hundred rounds through it today. I'll start by saying that I have an H buffer, RRA two stage trigger, M16 BCG, carbine length gas system, and 12.5" barrel.

four rounds fed, but the hammer failed to lock back. I'm not sure what would cause this, any ideas? I know the RRA triggers are notorious for crapping out, and I've got 2000 to 3000 rounds on this trigger so I know it's about time for it to go, but I was under the impression that they usually just turned into a single stage trigger.

Has anyone heard of problems with the disconnect or anything else wearing out in the trigger?
8/15/2010 11:17:41 AM EDT
[#1]
Broken hammer pin.
8/15/2010 11:22:07 AM EDT
[#2]
OK .. I'm slightly confused...

four rounds fed, but the hammer failed to lock back.


So are you saying you fed four rounds by hand (by the CH) and the hammer didn't lock back? (Then I would say yes something definitely wrong with the FCG)

Or was this after the first round went boom and then the hammer didn't lock back..and that happened four times? (In this case I would guess short stroking)
8/15/2010 2:07:03 PM EDT
[#3]
Quoted:
OK .. I'm slightly confused...

four rounds fed, but the hammer failed to lock back.


So are you saying you fed four rounds by hand (by the CH) and the hammer didn't lock back? (Then I would say yes something definitely wrong with the FCG)

Or was this after the first round went boom and then the hammer didn't lock back..and that happened four times? (In this case I would guess short stroking)


to clarify, I was firing from the magazine, and all of a sudden, the trigger wasn't reset, i'd charge the weapon, and a live round was in the pipe. this happened on four separate occasions, with four different magazines.

I know that with short stroking the bolt carrier doesn't have enough momentum to travel back far enough to chamber a new round, but if it traveled back far enough to strip a new round off the magazine, it's not short stroking...it has to travel like a fraction of the way back to charge the weapon as opposed to loading a fresh round in the chamber.
8/15/2010 2:38:40 PM EDT
[#4]
Quoted:
Quoted:
OK .. I'm slightly confused...

four rounds fed, but the hammer failed to lock back.


So are you saying you fed four rounds by hand (by the CH) and the hammer didn't lock back? (Then I would say yes something definitely wrong with the FCG)

Or was this after the first round went boom and then the hammer didn't lock back..and that happened four times? (In this case I would guess short stroking)


to clarify, I was firing from the magazine, and all of a sudden, the trigger wasn't reset, i'd charge the weapon, and a live round was in the pipe. this happened on four separate occasions, with four different magazines.

I know that with short stroking the bolt carrier doesn't have enough momentum to travel back far enough to chamber a new round, but if it traveled back far enough to strip a new round off the magazine, it's not short stroking...it has to travel like a fraction of the way back to charge the weapon as opposed to loading a fresh round in the chamber.


True .. but I have seen short stroking (new) rifles strip a live round but not reset the hammer but they usually quit after a good breakin.

But since the rifle was functioning fine I would inspect the FCG really closely ... look for any debris/blown primers lodged in/under the FCG.
8/15/2010 2:49:43 PM EDT
[#5]
I checked it out and can't get it to reproduce the problem by hand, also, I checked out the FCG and didn't find any blown primers or anything...I've been putting off buying a Geissele SSA...I guess this is as good as an excuse as any.
8/15/2010 3:19:16 PM EDT
[#6]
Quoted:
I checked it out and can't get it to reproduce the problem by hand, also, I checked out the FCG and didn't find any blown primers or anything...I've been putting off buying a Geissele SSA...I guess this is as good as an excuse as any.


I like the way you think.
8/15/2010 5:25:02 PM EDT
[#7]
If the bolt came back far enough for the spent case to clear the ejection port, the hammer was cocked back far enough, with the disco not retaining the hammer until trigger release/reset

So, the problem is in the disconnector.
8/17/2010 3:18:59 PM EDT
[#8]
Quoted:
If the bolt came back far enough for the spent case to clear the ejection port, the hammer was cocked back far enough, with the disco not retaining the hammer until trigger release/reset

So, the problem is in the disconnector.


plus1.. no way the bolt picked up a round without cocking the hammer back far enough.
8/19/2010 4:51:13 PM EDT
[#9]
Checked out the FCG? Did you take it out? I had the exact same type problem. Pulled the hammer & trigger group out and found a primer stuck under the trigger.
Just my 2C
8/19/2010 6:42:42 PM EDT
[#10]
I did pull it out. no primers or anything...I got my geissele in today so that got put in. Going shooting tomorrow. I may try the RRA 2 stage in a 9mm build and see what happens. Thanks guys!

Tom
8/20/2010 6:13:30 AM EDT
[#11]
The RRA two stage triggers had problems with the disco sear going weak, and in about the amount of rounds that you have through the gun, would either loose the second stage feeling, of the disco tension was so weak that it would not retain the hammer, and the hammer would follow the carrier back down.

Before dropping the RRA FCG into a new rig, give RRA a call to have them send you a new disco spring or two (will be free).
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