AR Lower build - hammer not releasing!

[Baron]

Hi all - thanks for reading this. I built an AR lower on a S&W stripped lower with one of Rock River's fine two-stage triggers. I am having a very peculiar and interesting issue.

On several occasions, the first pull of trigger (no matter how hard) resulted in a very quiet *click* followed by two seconds of nothing and then firing. Usually the remainder of the rounds were fine. You can imagine my frustration at this! It has been very difficult to replicate the problem; it typically happens only after the rifle has been sitting for at least ten minutes.

Well, I have isolated the problem to the lower itself. If I put my hand over the cocked hammer (to guard it from slamming) and pull the trigger, the hammer will not release if there is any downward pressure on the hammer - the same situation as described above happens. With my storebought RRA rifle, any amount of downward pressure on the hammer doesn't seem to matter and the hammer releases regardless.

All the parts are new; is there an easy place I could remove some metal and prevent this from happening?

Many thanks.

 

[navyretired 1]

When it's ready for firing what is putting pressure on hammer? It shouldn't be touching anything but sear if everything is fitted correctly. See if the hammer is touching the side of bolt sometimes or the hammer is sticking on something. If it only happens when you put pressure on hammer look for anything touching hammer and make sure trigger actually completely releases hammer. Is the trigger reset, is the secondary sear handed off to trigger sear. These are all SWAG's on my part because I'm not familar with RRA's 2 stage trigger other that stock style. Hope it helps

 

[Magnumite]

Do this unloaded: Remove the safety and see if the hammer drops normally. If it does, then the safety lug needs fitting.

What the small click may be is the hammer beginning fall but being stopped by the action. Do it now with the upper reciever off as you have done before. When you hear the click, try pushing the hammer down. You'll probably hear another click. That is the action group resetting.