Ammo is a big factor in making comps work effectively.
Compensators work on gas volume. One reason why a comp on a .45 ACP is nowhere nearly as effective as on a hot, .38 Super.
Gas volume and chamber pressure are not necessarily the same thing. You can have absurdly high chamber pressure with a fast powder (think Titegroup) and the comp will work much better with lower chamber pressure from a much slower powder (like HS6) that fills more of the case.
If I'm running a comp I will try and run the slowest powder that can safely drive the bullet I'm using at appropriate speed.
Of course it is necessary to handload for this.
thanks man, I appreciate the insightful comments on this post. The gunsmith actually scrapped the barrel while machining, so he refunded me. Maybe I dodged a bullet? ha
I have a few pistolas w/ fixed perm comps, and am always looking to experiment. I've read a study on the comparison between a comp barrel and a ported extended barrel. Both were effective in muzzle flip, with the comp being moreso. I've just never had a ported extended barrel so I wanted to compare for myself.
In response to the really helpful obvious comments on 9mm's muzzle flip, yes it has minimal flip compared to 45/38super, I'm always on the search for a flatter and faster follow up shot.