Joe, it's crude but works. A stand made with a washer tacked to the head of a 1/2" std thread bolt an 1 1/2" long or so can hold the rifle bolt upright in a small stainless boiler with a couple of inches of solution in it. You mask off all the rest of the bolt and just blast the back, and then adjust the height of the rifle bolt by screwing it up or down on the 1/2" bolt to immerse it just to the edge of the masking tape.
Don't let the solution come to a boil.
Piece of cake, Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time