I just got my order yesterday and as usual shipping was really fast.

One of the items I ordered was the RRA 2-stage trigger. After installing it, I ran into a problem where the BCG would get trapped by the hammer as I pulled the charging handle back. The BCG would not come forward unless I pulled the trigger. I tried the lower with 4 different uppers/BCGs, and as I got around to my older varmint rifle which also has an RRA 2-stage, I saw what I believe to be the problem - no notch in the hammer.

here's 2 pics of the new piece I just received:





Here's the RRA on my older varmint rifle.


The picture on the PKFirearms website also shows one with the notch like the older one I have.
You guys might want to test one of the other ones you have in stock. I am not sure how this design is supposed to work.

Should I send it back or break out the dremel tool?

http://www.shootingtimes.com/gunsmithing/ST_rockrivertrigger_200912/


this shows the one u have from PK
but on the RRA arms site shows your old one, maybe they change designs

An update:   PKFirearms told me to send the unit back and they will exchange it. A big thanks to them for the customer service.

I did try the new RRA unit in another lower and encountered the same problem, but I think I discovered the source of the problem is the new trigger/disconnector, and not the hammer as I had previously thought.

When I tried the new hammer with my older trigger/disconnector it worked fine.

When I tried the older hammer with the newer trigger/disconnector the same problem occurred.

The only obvious differences I could see in the older unit (bottom) and the newer one is that the disconnector spring appears to be more compressed in the newer unit..


After measuring I found the area just beneath the disconnector, where the spring is house is .281 inches tall on the newer unit, and .248 on the older one. I don't know if that is what is causing the problem, but it's the only difference I have found.

I not complaining about this because I know PKFirearms will make it right, it's just somewhat of an interesting mystery to me, and the first time I have encountered this type of thing in the dozen ARs I have built.

an update: PKFirearms sent me another one and it worked exactly like it should.  Thanks to PK for the great customer service.