The actual un-machined block looks too light to be reliable Vince - although I'm just saying how it looks from here of course. I think that I would hollow out that block and weight it with molten lead to give it more inertia to do its job. But it's all making a bit of sense now. You game to solve the 7.62 x54R bren problem once and for all Vince......? Followed by a few beers?