Hello tinker, 93x64mm, Ripp, & Daryl_S
Thanks for the reply.

Well, I have a range report ..

First off, I discovered the caliber is NOT 338-378 Weatherby Mag. The caliber is just plain 338-378 Mag, sans the Weatherby name. The 338-378 was pioneered by Elmer Keith in the early 60s. (1963) It was based on the Weatherby 378 case, but with sharp neck and shoulders. The Weatherby chambering was standardized and added to their line in 1998, and the cartridge had the standard double-radius neck and shoulders. Upon firing this rifle, the cases show the earlier version, which is in line with when this rifle was likely built. Interestingly, both Elmer Keith and George Hoenig were from Idaho.

I was amazed at the accuracy of this rifle, which reinforces my opinion that it was built for serious long range benchrest competition. The set trigger is a "wink" to shoot and each shot surprises you so there's no thoughts of a flinch. The heavy 11-3/4 pound rifle was a pleasure to shoot from the bench across front and back sandbags. Recoil energy was comfortable at near exactly 30 pounds.

as always comments are welcome.