Hi, Reb:
I've no hard numbers on the .35 Remington, but centre-fire barrels don't generally wear out, they burn out. So high velocity small bores like the .220 Swift and the .243 Winchester don't last as long as the medium bore & medium velocity rounds like the .308 Winchester and the .30-06. The match rifle crowd gave up on the .243 when they found a barrel couldn't make the 1000 round mark.
Generally the rifling at the muzzle still looks like new when the throats done. Sierra expects their test .308 barrels to last over 3000 rounds and they don't baby them. Time is money, so they fire 10 shot groups as fast as they can. Now a .35 Remington operates at 35,000 psi compared to 60,000 psi for a .308 and that means a much lower flame temperature. Combine that with the larger bore and I'd estimate a .35 would last 5000 rounds.
Actually the grooves aren't that shallow. Mine's .352" on the lands and .359" in the grooves. According to Hatcher's Notebook, .359" is the correct groove diameter and Remington Core-Lokts are maybe half a thou fatter than Hornadys, Speers and Sierras.
Bye
Jack