Mikey is correct, niether one is a 300 yarder.
When both are handloaded to potential, the 35Rem becomes a 200 yarder and the 375 a bit more, maybe 225-250 on the extreme outside.
These are brush guns, not sniper rigs. They were designed to be quick handling short range firearms.
There are much better firearms for long shots. You would do well with an '06 class (either 30 or 25), 6.5, .280, .284, 7mm, or a .308 for the 300 yarders, or any of the new short mags or super short mags with 150 - 180 gr bullets.
Ranger