9mm taper crimp die isn't designed to resize bullets, it's designed as a finsihing taper crimp to 9X 19 ammo....but all it is is a finely polished tapered hole in a steel die, no shoulders or edges. IT just happenes that the die at hand (RCBS) tapers to a .350-351" hole at the top, so a soft lead bullet pushed through the die (from the bottom up) pops out the top at about .351"
I did have to turn a .350" rod, making the ends dead flat. Tried making one with a "ball" end and I did come out with a slightly hollow based bullet once it had been sized, but it's too dificult to get the ball end centered.
Considering the very long taper to the die, it does a good job of sizing oversized bullets. Ran some of the Buffalo .36cal. conicals (.375") though the die and they also poped out at .351".
Do hav eto kick them in the butt rater hard to get them to slug up...micro powder charges just won't do the trick. With this long barrel, accuracy got better as charge weith increased. I use 40gr. as an accuracy load....at least at that level, the underhammer isn't blow back to set at 1/2 cock...but have gone up to 60gr. without any problems.