Mark I have a couple cans for my powder burners and they do reduce perceived dbs but not to the point of elimination of ear pro. 5 years ago I ventured into the PCP air gun world and my other weapons sit idle. My favorite .357 Mega Pitbull I use for deer is internally suppressed and very quite. Best part is it's not considered a firearm and BATF unregulated. I urban deer hunt and do some deer eradication at a few vineyards. No sound no issues.
Example:
Your never going to achieve that level of db reduction with a powder burner.