The fast twist special run RAR from Whittaker Guns.
I just went and checked that out. Pretty cool. Years ago I had Texas Trophy Hunter fever. This could conceivably scratch that itch. Ill have to do a little research of the heavier .22 pills. Sweet.
I've done the 22-6mm in a 1-14" ROT rechambered Winchester 22-250 barrel and have done the 22-243 Middlestead with a 1-12" ROT Hart or Shilen barrels twice. Both cartridges ate throat as if the barrels were made of butter. Even with judicious use, the barrels were cooked in less than 1,000 cycles, the CM barrel on the 22-6mm probably within 700. As with most things in life, there are trade-offs in that you have to give something up, like barrel life, to get what you want, an uber-fast .224" bore rifle.
