My only experience concerns the Dead Air Mask, which I purchased mainly due to the reviews stating that FRP was minimal. It does indeed seem to keep FRP pretty low and I'm pleased with the can overall. I'd likely buy it again. Bulk Automatch ammo from WalMart is subsonic in my S&W Victor. My 10/22 and Anschutz get CCI Standard Vel or the CCI HP Suppressor loads. Very pleasant.

[Linked Image from i.imgur.com]

Now with even more aplomb