So to generalize what I have read the more the rate of twist the lighter the grain of bullet I should use. Thanks to everyone for all of the helpful info and it looks like I will pick up some Hornady 40gr V-max for my varmint shooting needs and start to reload them after christmas when I get set up on reloading.
As the projectile weight increases, the rate of twist must increase as well in order to stabilize it. Conversely, the higher the rate of twist, the heavier the bullet you can use. As has been stated, 68-69 grains is probably the upper limit for a 1:9 twist bbl but it might shoot 75-77 grainers fine. You won't know until you try it. My 1:9 bbl likes 50-55 gr bullets best. YMMV. I see no need for bullets heavier than 55gr for varmints even out to 300+ yds. 40's will do just fine if your rifle likes them but wind drift will be more pronounced than with heavier bullets.
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