I don't think you have supplied enough information to say what the problem is exactly... "putting a metal prop on....". What prop, what engine, what airplane?
From my experience and reading the Lycoming chart, the LONG bushings, ie ones that might "bottom out early" are always called out for "fixed pitch" applications. I don't know of any in Lycomings that don't use the long bushings in that case.... so if you aren't using an "approved" prop for a Lycoming, STOP.... you are treading in deep water.
If you are putting a "fixed pitch" on an RV then of course the prop doesn't go on the crank... it goes on the prop extension, which goes directly on the crank.
If you are putting on a constant speed propeller then the bushings may well have to be changed and/or moved for the reason suggested in the previous post. The "clocking" of constant speed props to crankshafts is accomplished by this "key" method of long and short lugs.
If you are doing something to anything but an RV, I just don't have much help.
Good luck, cl