If shooting the 308 causes pain, you will save yourself a bunch of trouble down the road if you simply screw on a $350 8 twist 243 barrel and shoot 95gr or 105gr Bergers. They are going to be lighter on the recoil than any of your viable options with the 308 and will have substantially better wind drift and will hit whatever is downrange with more energy than any lightweight 308 bullet. Then you can make yourself a fortune by selling your scarce 308 components before the supply situation is restored. Win Win.