Looks like an oil filter suppressor on the MkIII
Thank you. I’d love to have one in my “arsenal” if they weren’t Class III with all the BS that entails. Starting with the insanely inflated prices that causes.
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.