Originally Posted by jasent
I would recommend a 20 shot group, of course not back to back, let it cool as normal but shoot 20 rounds with the same point of aim.
If you can't shoot a few dozen shots 30 to 60 seconds apart without bullet impact moving around, your barrel's not stress relieved correctly or it's not fit right to the receiver. More often than not, it's the latter.
Easy fix is to have a competant 'smith square up the receiver's front (face) with the barrel thread axis. It usually takes off no more than .005" of steel. Then shim the barrel so it clocks back in keeping the same chamber headspace. You'll need to rezero your scope as the barrel's probably pointing a tiny bit different relative to the receiver axis.