You may find that you will get acceptable accuracy with plain based bullets unlike me in my 404 where my cast plain based bullets sized to .424 and lubed with SPG or other soft type lubes, just will not shoot accurately no matter what I try. Using a small lathe I can turn down the bullet bases and apply a 44cal Hornady crimp on gas check and get superb accuracy from the same bullet.

Shooting plain base I notice lead splatters on the outside of the case neck, suspect the base is being affected by the hot gases and sloughing off some lead thereby affecting accuracy (my 404 has a lot of freebore for shooting mono bullets). My Hoch mould is a nose pour so has perfect bases but to no avail accuracy wise without gas checks.

I use my RCBS bullet pulling die and 44cal collet set up in the lathe 3 jaw with the bullet clamped nose first in the collet. The bullet spins perfectly true in this setup and I can run a slight shoulder on each base to allow a 44cal check to clip on by hand and then size in my lube/sizer. Can rattle off over a hundred bullets an hour using this method.

I did powder coat some of these plain base cast bullets but unfortunately used them for a 70th birthday fun shoot we had with my family shooting water melons so didn't get to gauge accuracy as such. The watermelons were all hit by everyone at 50m so was probably good enough for plinking.

Nose pour Hoch mould produces 400gr plain base bullets needing base turning down for 44cal gas checks.

RCBS bullet puller with 400gr cast bullet inserted in collet nose first (base of bullet in image turned down ready for gas check).