Well, it looks like I missed all the fun!
I think the original questions was something about turning the CSUSA Gentleman's pen, or Jr. Gent, on a PSI mandrel. This should work fine. The only hedging I might add is that PSI mandrels are just ever so slightly smaller than many other manufacturers mandrels. This and the fact that PSI makes their bushings to fit their mandrels, is why many PSI bushing may not fit other people's mandrels all that well. Now understand that this in not "the rule" but rather a possibility. In my own experience I have had only a few of the PSI bushings even seem a bit tight on my Berea mandrel.
So what's my point? Well, two things. If the PSI mandrel is slightly smaller (and "if" is the big word here) then there is the possibility that the CSUSA bushing may be a little sloppy on the PSI mandrel. If they are, it could cause the pen you turn to be slightly out of round. The second thing is if (again that "if" word) the mandrel is smaller, it might be more prone to flexing, which can also cause a pen to be out of round. Now these are pretty slim possibilities, but if anything, this would be why you may not want to mix one company's bushings with another company's mandrels. I find that usually it is not a problem.
I use some kits from almost all the different manufacturers. From PSI, I particularly like their Titanium slimline, and the Black slimline. I just like the shape of their clip!
Scott.