I need to fully understand why most after market single stage one piece triggers won’t won’t in a 9mm AR conversion? I understand a little or maybe I should say HOW DO I GET MY Velocity single stage 3lb trigger to work properly in my AR9? There’s gotta be a way! HELP!!! ASAP!
I believe your issue is going to be solved by using a “ramped” 9mm bolt. A non-ramped bolt requires a dedicated 9mm hammer.
Although I just noticed this post is quite old, I’ll leave my answer up for any others who might have the same question/problem.