Which 6mm chambering??

[Ranger3]

I have 6br, given your twist rat, I'd go in this order. 6br,6ppc, 6x45, you're limited to 60 plus or minus grain bullets. 6br is great all around caliber and very effective on prairie dogs. Brass lasts a long time. 6x45 brass is cheapest and would give you slightly less range than 6br IMO.

[Scott Evans]

A 14 twist may be able to stabilize a 65vmax at sea level. It should be stable at 4000ft elevation. PD's are found at ~2500 ft and up.

6BR and a 65vmax at 3400 tears PD's UP.