I'm looking to build a 9mm upper and currently have an Vltor A5 system with their A5H2 buffer (5.33oz) on my RR. I am looking to purchase a buffer with my goal being a smooth, safe SMG.
The heaviest buffers I've seen are the Vltor A5H4 (6.83oz) and the XH (10oz) from
Heavy Buffers. While having a sufficiently heavy buffer seems to be the primary concern I've also read that limiting bolt over-travel to protect the bolt catch is recommended. It looks like most people are adding spacers if they use carbine length buffers/extensions or they buy purpose-built buffers like the
9mm-Q (which appear to be A5 length).
So my questions are:
1. What weight should I get?
2. Should I be concerned about bolt over-travel and, if so, how should I address it?
Also, what barrel profile (weight) is appropriate for a FA 9mm upper?