I turned on the lathe the other day and made a new neck expander for 7.62 Nagant. Original on the left,just-tried-out on the right. The expander shank is longer, and shaped a bit different at the base. If you're not familiar with this cartridge, the bullet actually sits down inside the case
like this. The original expander is from the Lee die set, which is actually to form and expand 32-20 cases. Which works, but they're much shorter than actual Nagant cases. I covered forming .223 brass to make full-length cases here; the expander works on them, but doesn't go deep enough or quite large enough. So I found a suitable piece of steel and turned this new one.
I just finished loading fifty rounds, and this new expander does make a noticeable difference when seating the bullet, so this was well worth doing. It's not drilled like the original for charging the case, but I never used that feature so it's not a loss.
Note: If you've seen the newer factory loads for this cartridge, you'll notice they have a very severe crimp of the case mouth. Back when I got the pistol I also got a box of Russian target ammo, and it did not have that crimp; it was a simple taper of the case. So that's what I've done, and it's worked well.