It wouldn't be any worse as long as the muzzle was cleanly faced off perpendicular to the bore line, and no burrs remained. But one little bump or ding on the muzzle afterward, and all bets are off. A big part of the crowns job is to protect
the end of the bore and rifling.
If I were to leave the saw cut end of this barrel blank as-is, it wouldn't shoot worth a hoot!