Mike TX
I suggest conservative loads for your 338. Don’t push pressures.
Being a small ring means the barrel shank diameter is smaller. The wall thickness of the small ring barrel gets pretty thin when the chamber diameter increases from .473 to .532”. With hot loads it is possible to expand the barrel’s chamber area enough to crack the receiver ring. Case hardening is done primarily to eliminate lug set back but doesn’t add any hoop strength. Either Jim Borden or Dan Lilja has written an engineering analysis of the issue.
There have been many 416 Rigby’s assembled on M70 actions. They are OK since if the original pressures are kept very low but I have seen them have trouble loaded to “modern pressures”. Again the issue is because the wall thickness of the barrel shank is pretty thin.
You should be good to go if you keep your 338 loaded down to 338/06 type performance and as a benefit you will decrease recoil and have great brass life.
