Smaller bores and higher velocities wear out faster
Totally agree.
The rule of thumb that a 308/30-06 barrel peaked at 3500 rounds, was worn out at 5000 rounds, is still reasonable for 600/1000 yard shooting. I have shot outstanding scores on the 300 yard Reduced target with a 308 barrel which was so worn out it gave poor results at 600 yards.
Sub caliber shooters, target shooters have migrated to 6mm and 6.5 mm bullets because excellent match bullets finally got to market, and the ballistics are excellent. However, cartridges like the 6.5-08 are real barrel burners. I have asked shooters using them, if they last 1700 rounds that is a reasonable life. The 243 Win is an outstandingly accurate round but its target lifetime is around 700-800 rounds, per guys who use them.
I met a target shooter who was using a 22-250. He told me he shot very few rounds through the thing, probably around 800 rounds a year. When he had the rifle rebarreled, he said on the old barrel, the rifling was gone for a foot in front of the chamber.
He also said, he used a lot less windage at 600 yards than the .223 shooters all around him.
The trend is towards rounds, like the 6.5 Grendel, that are slower, probably lower pressure, but certainly push less hot powder through the barrel. Tubb came up with the 6 mm X, a smaller case, keeping the excellent ballistics of a 6mm but pushing it with less powder.
At least that's what 'Brassey's Essential Guide to Military Small Arms : Design Principles and Operating Methods' said
I don't think the younger generation reads books anymore.
Good that you do.