Re: 22-250?
The .22-250 is an outstanding varmint caliber, but barrel heating can be rapid, can rob accuracy, and can create a rapid throat erosion situation. The chambering is best for applications which do not require sustained fire or a rapid firing cadence.
My .223 is 1:12" and doesn't seem to do well with bullets over 55gr. Sierra recommends a 1:10 twist for its 69gr bullets.
Greg