I would never do a 300/221 without an adjustable gas block due to the wide variety of loads out there. From slow subs to fast light super loads.

Although first thing I"d try is to make sure the gas block on the gun is indexed correctly so its not blocking part of that port.

I don't think the port on my 300 blackout barrel is 1/4 inch or close, but I stopped the build on that years ago when I realized I'd have action noise to deal with along with the suppressing noise and moved to a bolt gun for the subs.

I don't recall if my adj block is locked in place yet or not, if its not I'll measure tonight and post again...

We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....