What powder and grains are you getting with the 135's at 3100?Gotcha.
My 18" prc runs a 156 at 2820. 143 at 2925. 135 at 2985.
My 22" prc, 156 2920, 143 3040, 135 3100.
Just to give you an idea of what that cartridge can do in a short barrel. The 162 7mm is a great choice. I'd like to see a 160 6.5 but the only company making those used to be matrix. Good bc but didn't make a great hunting bullet in my opinion. It penciled on yotes.