[DUMBGRUNT]

If that 9mm, get much over 1100 fps, it will break the silence all by itself, also the action makes some noise.
Firing from an open bolt also is noisy, and I doubt that it can be disabled.

In RVN we had a few ‘silencers’ for the M-16s, when used the gas valve is closed. Still had the crack of the sound barrier, but that was all.

Only a few rounds and they had to be repacked.

[mountn man]

I remember you telling me that, a few years back.

Hard to believe it's been at least 14 years.

(I knew a fitter, Sue Cunningham, married to another fitter... Richard Cunningham)