Way off topic. A 250 will do what the OP intends. My point is 6 CM brass is better.....much better. 6mm bullets are off the chart.
Be sure to find good brass before you embark! I just hate [bleep] brass and a bullet compromise
Looks like a nice build..rock
Hornady makes pretty decent brass and I've never had any trouble getting good accuracy from ammo assembled with Winchester/Olin component brass.
There are plenty of .257" component bullets that are capable of producing MOA or better accuracy and performing as designed on varmints and game.
While the 6mm CM may have a potential accuracy advantage over the 250-3000 due to the availability of competitive grade components, how relevant would that advantage be when the parameters set by the OP are factored in?
