An interesting point I don't see made often regarding barrel wear and throat erosion is how far down the barrel it extends.
When we discuss erosion, I think it usually sounds as if the affected area is mainly relegated to just the throat, but in fact, it extends a LONG ways down the barrel.
For example, I recently scoped out:
~800 round 6XC
has had 500 fireforming loads with the Berger at 2950, and about 300 full power loads at 3140fps.
Shot at matches and for some recreational target shooting
Melonited Benchmark barrel
Shows some definitive erosion in the throat and heat cracking extending 6" or so down the bore. Not in bad shape, but certainly shows as USED.
~2000 round 284Win
loaded with 175smk at 2825fps
Shot mostly at matches and some target shooting
Krieger 4 groove barrel
Shows *well* used but not trashed, small chunk out one of the lands just ahead of the leade. Heat checking extends 6-8" down the bore
~1800 round 260
run with the 142smk at 2830fps
mainly been used for match shooting and spirited target shooting. Not babied
Bartlein 5R
Shows the worst wear of the three barrels. Throat is eroded, significant heat checking for 6-8". Heat cracking/checking is present all the way to 15" or so down the bore. Doesn't appear "trashed" but looks like it's well past 1/2 life.
Anyway, the point I'm making is the erosion isn't *primarily* focused right on the throat. Yes, the throat is the worst, but it's not as if the rest of the barrel isn't also heavily affected. It is.