Hi guys
I have just acquired a Savage made No4 Mk1 303 and want to start casting for it.
I took it to the range yesterday and it shot 2 1/2" groups and no keyholeing at 100 yards with factory sporting ammo (pretty sure they're .311) and I'm pretty happy with that for an almost 70 year old rifle that I don't know the history of.
Now my question is, what size cast boolits should I go for? I slugged the barrel today and it came out at .314
Would a Lee .312 185gr boolit be fine in a .314 barrel or should I go up to a Lyman .316 mold and size down to .314 from there?