Adjustable Gas Blocks with suppressor usage

I have a few AGBs on my rifles. Mostly to increase the reliability of running them both suppressed and 'open header'. I believe a few of the AGBs I have are "bleed off" type (Superlative Arms being one) as opposed to "restriction" type.

Is it possible that the bleed off versions are creating unwanted noise when running suppressed with subsonic ammo? This would probably only be an issue for me using 300Blk as it's the only subsonic rifle ammo I have. Is there enough noise coming out of the BCG/ejection port already that it doesn't matter? Is there a way for me to test or measure this?

Sure, it can be measured, but requires very expensive equipment to perform properly.

Suppressor companies often measure the SPL at the shooters ear.


Sometimes they can just tell with your ears.

For example the Gemtech SBC has significantly more port noise on the suppressed setting, venting out the port.