What is the difference between a taper crimp and a profile crimp, and which, if either, is better for schuetzen or standard single-shot loads? I've always used a taper crimp on everything from 38-55 to 45-70 and I'd like to improve the process by crimping with separate crimping dies after seating the bullet.

Vall's answer is just what I'd have said.

I'll add when I am crimping, I use the same die to seat in one step with the die turned out so the case mouth doesn't reach the crimp, then back the seating stem off and turn the die in to crimp in a second step.

If you want to tighten the ring on your crimper to keep a consistent crimp, you can use one of the RCBS washers for switching between 38/357 to hold your set die high enough when turned in against the washer that it doesn't crimp, then back the seating stem off and remove the washer from under the die ring.

I always seat and crimp in two steps unless I've got a very generous crimp groove on the bullet.

I'm with Beltfed here. The amount of belling is really tiny in my case, so the extra two or three thou can be felt going in. Not hard, just noticeable. Some cases don't even get sized to reload.

I do not crimp SS nor do I remove the slight bell.  Neck tension holds the bullet.

Same as the other guys, Single Shots no crimp very little bell and even less removed when seating the bullet.

Fixed Ammo that is. Breech seating nothing at all.

That's the trick less you do to the bullet better off you are. Some matches fixed is needed for one reason or the other. If not better if the bullet is undisturbed mold to up the barrel

Your Marlin another story, needs some crimp to hold the bullet in place against the magazine spring. However own and have owned a number of Marlins used with lead bullets, very little crimp. Looking at some 25/20's for my Marlin 94 now even magnified hard to see any crimp.. 

25/20 has a long neck friction alone holds the bullet in place

Boats

When breech seating, I put a tiny bell on as well, at least if there is some smoking of the case. Like mentioned earlier, it prevents some blowback of gas.

I have always thought that with soft lead / tin bullets that crimping does more harm than good. Deforming the base half or so of the bullet before the case can be expanded by the blast of the powder. The belling makes sense to me, as this is what I do with all my BS cases to insure that all the power of the powder is directed against the base of the bullet.

40 Rod

Keeping the brass the same length helps a lot