.44-77 PP bullets.

[Nuclearcricket]

Sam, That long taper is a plus for sure. That helps from getting a ecentricbump on the case mouth. I always wondered why Meachem bushing dies did not make them that way.
With those bushing dies if you don't have a good fitting shell holder or don't have the case going up straight you get an uneven reduction.

yes it does help center things but the 8 degree is also the shoulder angle on the 77 case. I have used the bushing die to neck a 45-70 case down to 44 with no problems and have necked one clean down to 44-60 length. One pass and it was done. I used a 348 Winchester shell holder as my regular shell older is too large of a diameter to work with the Co Ax press.
Jim as to material for the bushing, all you listed would work just fine as would some prehard 4140. It just doesn't polish up as nicely. The last bushing I made I used 8620. Polished up like a mirror but does need case hardening. I don't have a selection of tool steels like you do and mostly what I use is 12L14. or aluminum and brass. But any steel that you can harden will work well.
Sam