Most of mine shoot 150s well enough, but 170s better.
Trying for the fastest load is not always the most accurate choice. Either try a wider variety of loads, or switch powders.
Opinions will vary, but I have found other bullets to group more easily than Sierra.
It is hard to beat IMR 4064 and 3031 in the.30-30. Other powders may brag a little more speed, but they are a proven powder in that cartridge for many years.
I've had good luck with the Speer 170 Soft Point Flat Nose.
