Im looking at a several factory rounds that could have the rims rebated easly on a lathe or possably a drill press jig in possably a one step operation with a custom ground bit. they are all shorter than the 308 WIN overall loaded length. the first is the 444 marlin it uses the 44 mag pistol bullets . the 45-70 and the 450 Marlin (basicaly a 45-70 MAGNUM) there is also the 458x2 american and a couple of other wild cats.
the 444 marlin brass is $45 per 100 it would alow the use of pistol bullets of 430 dia and 44magnum barrels could be rechamberd and also would use the same bullet as the new 450 bushmaster.
the 45-70 ($42 per 100) and 450 marlin brass( $81 per 100) would use the .458 rifle bullets. I would likely rebate the rim to standard 7.62x39 dia but a 308 WIN size rim could be used and the bolt opend up if it makes the rebating process eaiser or if the smaller rebated size is to much for that case. there are loads for all these rounds from 14,600 PSI clear up to 45,000 PSI so im sure a safe load can be found. these rounds should fit in a modifed G2 mag or other 7.62x51 MAG. the 450 marlin head spaces on the magnum belt so keeping the belt and rebating it may be a little tricky. there is no need to use it anyways as the brass is way higher than the 45-70 brass and those have been loaded hot in modern guns for years. there is no reason the AK needs to be stuck with the same short rounds as the AR. rebated rimmed ammo would still use the same chamber as the factory stuff. also rebating the rim would prevent hotter factory ammo from chambering.
the 458x2 american uses shortend magnum brass. I just know that I need to do something with this 458 win mag barrel