I've already got the barrel vise, and rosin - just need the correct bushing. The brownell's vise has a 1+3/4" opening. Fleabay bushings all seem to be 1+1/2 od. Only the steel bushing no 5 was in stock - it should fit? Am I right the Mauser 98 shoulder is 1.2"? - the a3 seems 1.195, which is why I asked about a few wraps of aluminum tape, then the steel no. 5 bushing in the vise.
If it's not the right size, it will be a long wait I suppose - or make my own with wood blocks as you suggest. I'm in no hurry, and I already left my disappointment at not getting it done this weekend in an empty beer can...which I suppose I could make an aluminum shim out of for the steel bushing if it's a bit too big?