I've had good luck running an H3 buffer with 9mm, .223, and .22lr on the same lower. I don't have the bolt hold open feature with 9mm or .22lr but it's not a problem for me. Just pull the mag block and and swap uppers. The mag block is the top loading Hahn and the 9mm bolt is unramped. Stronger trigger and hammer pins are a must with the 9mm as well.
Where and how much is the least expensive A2 stock kit?
Does the RRA 9mm hammer work on the .223 and .22LR?
Where does one acquire the stronger trigger and hammer pins? I suppose "stronger" means "stronger than the AR mil-spec"?
The RRA 2 stage hammer will not work with 9mm. I haven't looked at the regular fire control group from RRA. The hammer in my 9mm lower is a regular LMT hammer. The part to check is at the top of the hammer, if the hammer is rounded it should work fine. The RRA 2 stage has a notch on the top that hangs up on the bolt. I'm able to run all three uppers on the same lower with no changes other than removal of the mag block which takes about a second.
As far as the pins... I like the KNS pins, they don't have the notches like regular pins.
Thank you.
My lower would not run a .22 upper with the RRA 9mm hammer installed. I swapped it for a regular DPMS hammer and it works great. The regular unramped bolt resets the hammer in around 1/2-3/4" and with a ramped bolt it makes it 1.5" or so to reset the hammer. It just makes the whole deal happen a little less violently to protect hammer pins and lower holes.
Which one is less violent?
The ramped bolt.
I have a spacer that you use that you can have. I bought it because I wasn't sure if I needed it. It is for A1/A2 configurations so the buffer doesn't go too far into the buffer tube. It is just a plastic cylinder. I assume it goes in before the spring. Then the spring, then the buffer, but I'm not sure.
Gah, that's what I have in my AR lower now, and I love it. Guess I should spring for a dedicated 9mm build and have done with it...
Thanks for the comments and suggestions, guys.
Oh, what about magazines - any recommendations for a 30-32 rounder?
