The USN marksmanship unit rebarreled their match grade Garands when the gauge read 5; typically about 4000 to 5000 rounds. Your barrel's got a lot of life left in it.
Regarding the muzzle, I've seen no degradation of accuracy if an M1's muzzle is so worn form steel cleaning rods that there's no copper wash back for 1/2 to 3/4 inch. That's evidence that the metal's been worn away quite a bit. But its the same for every shot fired; doesn't hurt accuracy.
On the other hand, if the crown, the edge at the end of the rifling at the muzzle angled face is chiped or damaged, then a crowning tool will need to be used to clean it up.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Last edited by Bart B.; April 26, 2013 at 03:59 AM.