You probably won't need a new barrel unless that one is shot out in the throat or the lands are funneled open at the muzzle from use of the segmented steel military cleaning rods. There are gauges available from the CMP to check both. If you are a one-gun Garand owner, see if you can find a gunsmith with a set to check it for you?
Take a felt bob on a Dremel tool (I know, I know, but this is gentle) and some JB Bore Compound or Iosso Bore Cleaner or Brasso and polish the pits and their edges. Those polishing materials should not remove enough metal to matter. You just want to round the edges of the pits so they can't grab. Flitz will work, too, but will take longer. When you shoot the gun, watch to see if you build up jacket metal in the pits? Removing a little metal from a bullet won't make a hill of beans worth of difference to accuracy, but if you have that building up you are beating on the bullets enough that they may tip in the cartridge case and be a little less accurate at long range. If you have any feed problems and the hang-up is always when the cartridge feeds on the pitted side, that would be another indicator it matters. Neither of those situations are likely. This is a battle rifle, after all, and is designed to keep working despite a degree of abuse.
If you look at your bolt, you'll see most of that cutting at the breech end of the barrel is profiling that allows the bolt to cover the case head as far as possible. It has to leave room for the extractor to snap into a case's extractor groove. The rib at 6:00 doesn't fit into anything. It is just a left/right feed ramp division to guide bullet noses coming off the staggered magazine stack into the chamber without bouncing over to the opposite side. I suppose the general funnel shape makes it a little easier to toss an individual cartridge into the chamber if you don't have time to insert a fresh clip?
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Last edited by Unclenick; November 26, 2008 at 07:47 AM.