Now I’m going to be tearing my files apart trying to figure out if the “as NIB” Combat Elite I bought from a pawn shop 20+ years ago came with the box or manual. I think the first I knew that it had the collet bushing was when I disassembled it. It’s not like they put it on the price tag.
Sorry about that.
I was taught to always turn the barrel bushing with the barrel out of battery -- even with a solid bushing. The bushing is much easier to turn as the barrel diameter behind the muzzle is often thinner, and this practice prevents wear on the crucial barrel/bushing interface used to locate the muzzle of the barrel when in battery. The latter is a big deal with Bullseye pistols. Most of my Bullseye guns were fit so that the barrel bushing cannot be turned when in battery, even with a steel bushing wrench. Les Baer fits his guns the same way although part of his fitting leads to sprung barrels, which is not good for accuracy.
With match guns, I remove the slide stop, pull the upper from the frame, remove the recoil spring and guide, slide the barrel forward, and then turn the bushing.