For those in the audience, it's MaNson. Manson reamers is a well-established and venerable company for powder-burner reamers and gunsmithing tools. The tool shown was really designed for manual use (i.e. without a lathe). If you choose to use it in a lathe that's fine (and probably works great), but unnecessary, imo.
Ignoring chokes, pilots come in two flavors: fixed and rotating. If you use the rotating pilot, Manson (and all the other reamer makers) offer 'kits' with pilots in 0.0001" intervals. Which is to say, excruciatingly exact. Find the pilot that just slides into your bore (where the next size will not) and you have something that will accurately center your tool. Kinda* Fixed pilots are typically cut to nominal size and are really made for hand reaming, where you need something to guide the reamer, or other cutter, along the path of the bore. The pilot or the bore spins and may result in marring, but properly used this doesn't really happen.
In a lathe you can set everything up rigidly, in which case you don't want a pilot trying to move stuff away from where you have it set, or you can use a 'floating' reamer / cutter holder in conjunction with a piloted tool to try to let the pilot guide the way. You still have to set stuff up pretty much centered as the 'float' is usually only a few thousandths and you really don't want to use even that much. Because I have a lathe, I'm mostly in the first camp - rigid setup, dialed in exactly as I want it, and no pilot, but there are times when I will resort to a floating reamer holder - sometimes out of necessity and other times because I don't think it will matter and the piloted tool is more convenient.
I really don't have the experience to speak about the effect of chokes - definitely a complication for a piloted tool.
"All this I say by way of discourse. I should not speak so freely were it my due to be believed." -
Michel de Montaigne GsT
* The fact that the bushing can spin is proof that there is clearance there as well. So, although a bushing might be fitted to within 0.0001" (do you realize how absolutely close that is?!!!) there is some additional clearance for the bushing 'axle'. Using my calibrated fingers, I'd say it's somewhere around 0.0005", so significantly more 'slop' than the fit of the bushing might suggest. Of course I have only a few bushing sets (they're expensive) and mine might all be from the same manufacturer, so results may vary...
