I seriously doubt the GCA is making this up, they went to great lengths to do the testing.
Forget about the steel rod /muzzle wear arguement. Wheres the poroof that barrels are wore out with MW of 3?

I'll gladly pay the shipping for any Garand barrel that isnt pitted ,doesnt not have a dark bore, with a Muzzle wear of three. Let me know how many you have and what shipping cost is