Re: Building a 6.5-284
the 120 would probably shoot fine with a 1-10 twist BUT , I personaly would get a 1-8 just incase you want to use a heavier bullet latter down the road.
Speeking of heavier bullets , what makes you want the 120 Ballistic tip? I'm having a 260 built and plan to shoot the 140 A-max , its got alot better BC than the Ballistic tip for the longer shots and the bullet is alot longer so it has better sectional density wich will allow it to penitrate a little better but its still a pretty fragile bullet to allow good expansion.
Not trying to sway you one way or the other but I persoanly would get a 1-8 twist just in case you want to try your hand at longer ranges , or bigger animals
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