they really have cut some corners lately.
the new steel cupseal shaft is rough as a cob and fits rather loosely in the body.
if you have a gun with poor efficiency, I suggest you check into getting a valve job.
I used 400 and 1500 grit paper on my shaft and now it's
a mirror, wich anyone can doo. This will keep the valve body hole from wallering out over time.
The big kicker is resizing the hole in the body. this would be easy if you wanted to make it larger, but of course you want it smaller. No big deal if you have a 1/4" collet, but don't go too far.