Depends. If your gun is really OLD, or of eurpoean origin, it may have a .223/16 twist bore. .224's would work, but reduce your loads and work up cautiously.
This is a picky caliber to load for, but not that difficult if you have good reloading practises. Chamfering really helps seating flat base bullets without crumpling the thin walls. Collet sizing improves accuracy and brass life. Carefully individually weighed charges improve accuracy more than for most cartridges.