it's sad, I learned to shoot semi-auto really well but now that I'm learning bolt actions and other action types.. man recoil really throws off that dainty and precise technique shot to shot, and moving to crank a new round in the chamber all the time, and scopes have scope shadow....
anyways, my rifle is a remington 700 vtr, the muzzlebrake/triangular barrel type, 22" I think, 1in10twist, light rifle but there is a brake on it so I think that 43-44 should be easy in anything a bit longer and heavier without a break, or with a "real" stock instead of tupperware
oh, don't forget that using 7.62 vs actual 308 changes case capacity, I think your 42 is actually about max w/ 7.62 (military brass is thicker so it can handle the higher pressures caused by the slightly reduced capacity but it's harder on the guns using it, and primers can rupture or back out unless you're crimping the primers inside the case-I have no idea how that's done so ask someone more knowledgable than me if you try it)
man I was thinking about going to something lighter and/or using a slightly slower powder too, make more push than punch out of the recoil
along with that r3 recoil pad (makes a 300 win mag a 12ga, makes a 12ga a 308, makes a 308 ... comfy with the right loads)
OHHHH, one last thing for real this time, I got high scope mounts so I can see under my scope/between the mounts/along the barrel so I can shoot it like a shotgun up close (might not be able to call the shot placement but I'll hit something way too close to focus on with a scope if the light is good)