Probably because a ramped 9mm bolt will work with standar ar hammer and you'll need a 9mm bolt anyway. The problem has been solved already just with a different component would be my guess.
m16 hammer with the hook removed works with both!!!
Thanks.
I'm considering an upper, possibly with an integral suppressor.
I very much like where your heads at, That would be awesome. My build was a cmmg upper, dedicated lower, and barrel and no complaints here. Got a yhm dedicated 9 lower awaiting budget freedom for completion. Do share if you get one!