Going to have a coyote/varmint gun put together this year, would like to go with a 6mm of some sort, I'm in central Pa, so don't see many shots over 600yrds, what bullet weight would you guys go with? Getting ready to order a barrel, so trying to come up with a twist rate, also would a 6x47 lapua give better barrel life than say a 243 or 6cm? Thank you