you are almost certainly MIS-remembering the accuracy of your old barrel. CONSISTENT (as in ALL THE TIME) 2MOA is what you might expect with match handloads in a well set up non-match prepped M1icon. ABOUT 3MOA is all you could expect with LC.

I have a full match prepped CLint Fowler rifle which MIGHT hold 2MOA with LC surplus. The stuff is DOO DOO for any hope for accuracy.

HXP might get you a bit better groups than LC ball, but not much more than a HALF MOA.