Unitizing the gas cylinder, either a screw and glue or welding, and shimming when reinstalled well do more for accuracy than about any other mod.
Article on shimming,
On the barrell, Springfield M1A Loaded model MA9222 has a 22" 6 Groove 1:11 right hand twist national match medium weight premium air gauged barrell (Springfield's description), so KraigWY I guess it should be a good match up with the Federal Premium Match 168 grain ammunition.
Wilson six groove that SAI has been using for years. Those 3/4" groups are good from your rifle.