A 22-250 is not a long range Varmint round, unless your only killing prairie dogs and ground squirrels beyond 350 to 400 yards when you use the heavy for caliber bullets.
When ground hogs to coyote are considered Varmints,,, those heavy slower moving 70 and bigger bullets are much better intended for showing off on paper! Where the bullets in your class still offer enough terminal performance to open up and act as a real Varmint Bullet. They kill on marginal hits, where the heavies just poke a hole!
I'm old school, and if you can't kick em, in my world, you can't count em!
"I hear this fast twist crap gives as good a accuracy as slower twist with light bullets, but let's you shoot heavier."
Only one thing is a fact in that quote is one thing, it let's you shoot heavier bullets! But it dam sure won't produce the accuracy with lighter bullets that a slower twist will!
I hear it all the time, but anyone who has competed with the finest shooters in the world from short range extreme accuracy, to long range knows, you'll never get the accuracy with a fast for caliber twist to compete with those shooters in short range Bench rest!
Same goes for a slow for caliber twist in long range Bench rest beyond 600 yards.
Those are facts that have been proven for decades, without exceptions. I just wish so many would quit giving this bogus fast twist will do both BS for advice to those that don't know no better!
Now to answer the OP, most here have given you the best answer to your question, 50 grain to 60 grain,, 12 twist is your huckleberry! This is probaly the twist that makes the 22-250 as good as it gets for the purpose you mentioned. It is for sure the twist, and the bullets I would rely on for the highest success rates when killing at any range with a 22 centerfire was my goal, and higher wound percentages are not!