My personal fav for .243 is 4000MR, very consistent and accurate. IMR4350 is a close second. You can cover .243, .270 and .30-06 with the same powder, something in the IMR4350 burn rate range. the .23 and .308 will need something a bit faster, down around IMR4895 or W748 burn speed range. IMR 4064 is the closest thing you could get to a universal for all. There are loads listed for all but the .223, its far too slow for .223. I personally would use IMR4895 and IMR4350 in your situation.