I have tried both the 22-243 Middlestead and 22-6mm (22 TTH?) in 1-14" ROT rechambered 22-250 barrels without great success.
The 22-6mm was a post-'64 and pre-USRA Winchester 70 and was the fastest throat burner/eater that I've ever owned. The 22-243 Middlestead was only slightly slower, but appeared to be much easier on the barrel throat.
I have decided that, for me, the 22-250 and 22-250AI do everything that I need a larger capacity .224" bore rifle to do. If I need more performance, I'll just take a 243 or 257 Roberts or 25 WSSM out of the rack in lieu of a .224" bore rifle.
Jeff
