I've been shooting F-Class at 600 yards for the last 6 1/2 years whenever I have time, which is typically only 2-3 times a year. So far I have only used .308 rifles, including my FN SPRA1, a Howa Varmint 20, and a Savage 10 with 26" barrel and B&C stock. Lately I seem to be the only person...