AR-10 trigger problem

[Bottom Gun]

I put a RRA 2 stage trigger into my Eagle Arms AR-10. I am having a problem with it that I cannot figure out how to solve.

The trigger will sometimes pull like a two stage should but it will sometimes pull like a single stage and you cannot feel the second stage step. It seems to pull a bit lighter at these times as well.

With the upper receiver removed, the trigger pulls just fine every single time. Just like it’s supposed to.
It’s when I close the rifle up that it starts getting squirrelly and sometimes pulls like a single stage.
I do not have the same trigger pull from shot to shot with the upper in place, only when the rifle is open.

Has anyone else ever had a problem like this? Any suggestions?

I was thinking about waiting until the new McCormick two stage triggers are out and trying one of them but if I can solve this problem, I won’t have to.

Any help will be greatly appreciated.

Thanks!!!

Ken

 

[rbernie]

Upper open or closed shouldn't matter, as far as I know. I suspect that there's some goombah (primer or such) that's rattling around in the FCG and is getting in the way from time to time.

I have a Jard single-stage in my AR10 and love it. I have a flat single-stage CmC in one of my AR15s and it's nice, too. However, I don't think that CmC makes one specifically for the AR10, and I seem to recall hearing that the hammer width on an AR-10 was different than on an AR15 (making the AR10 FCG non-compatible).

Hopefully, somebody who knows more about AR10s will be along shortly.

 

[Bottom Gun]

I agree there should be no difference. That's what has me puzzled.
The rifle is clean as a whistle. There are no fragments of primers or crud in it.

I did hear something about the hammer width, but wouldn't that prevent the hammer from falling altogether?

I have these RRA triggers in two of my AR-15's and they work perfectly.

 

[rbernie]

It may be, come to think of it, that the bolt carrier is holding the hammer off the release slightly. Dunno if that's possible with the RRA two-stage, but it's as close to an explanation as I can get.

Look at the stock Armalite hammer and look at the RRA hammer. They *will* be dimensionally different - not just in shape, but in thickness and possibly height/width.

 

[Bottom Gun]

Good idea. I don't have the old hammer here with me, but I will measure and compare them both this weekend.
Thanks!!