I have a 3/1944 built Garand.  On this Garand originally came a 9/46 barrel that has a TE of 2.5 and a MW of 2.  I happened across a 3/1944 barrel that specs out @ TE 4 and MW of 4.  For shits and giggles I installed the 3/1944 barrel.  Much to my surprise it is MORE accurate.  The headspacing came out EXACTLY the same.  Both have nice bright bores and chambers with sharp rifling.  I would have expected the 3/1944 barrel to give up a bit of accuracy.

There are myriad reasons why a barrel is accurate or inaccurate. Muzzle wear and throat wear are just two of them. It is possible that every other factor on that barrel is within the zone so to speak. These factors together, in this particular barrel, override the throat and muzzle wear.

It could also be that you are employing better shooting techniques.