I suppose the patcher lady could have done that, or pressed it down on a rounded peg and twisted the bullet. I will try a rounded dowel and see if the effect is similar.
Unfortunately, I started tearing apart the bullet before the taper question came to mind but it looked pretty straight when I calipered it.

I don't think the disc wad was loaded wet because the edges look cut. My guess is that they were punched from a laquered sheet. Also, the patch is very clean looking where it was tucked which leads me to believe the top wad was totally dry before loading. Didn't stick to the top wad either.

As for the tube, it would be a fun project to hollowpoint some 500-577 bullets and press in a .22 short case. Or, press in a .22 blank and try for an exploding projectile! Might need to hit something like rocks to get it to pop, but maybe not.