I'm seriously considering the purchase of a nice older .375 Weatherby (non-Wby rifle). Does the .375 Wby/JRS/AI/etc. provide any real performance or reloading enhancement over the vanilla .375 H&H?

My assumption is that there's no meaningful difference in performance, and that my decision should be made purely on the basis of whether I like the rifle.

Thoughts anyone?

Sure, you obviously have to like the rifle. If you do there are no flys on the 375 Wby. You are looking at ~250 fps in speed increase and about 1000 lbs more energy at the muzzle compared to a 375H&H both using 300 grain bullets. The Weatherby is an interesting round.

Ken....

My Africa hunting buddy has one, on a Brno 602 action. I don't think there is any significant difference on the classic 300 grain bullet that would truly effect hunting performance. Probably the best advantage is when using heavier than normal bullets, like 350 grain + bullets. There, it really might make a useful difference over a .375 H&H. Could be useful for buff.

Wink,
You are on the right track.

Advantage of the .375 WBY over the .375 H&H:

250 fps with 350-grainers.
200 fps with 300-grainers.
150 fps with 250-grainers.

Something like that.
The heavier the bullet, the better the WBY,
due to fortuitous conjunction of conditions involving usable powder burn rates and charge mass in the available combustion chamber.

This assumes one is comparing the standard tight-throated .375 H&H to current (2001) .375 Wby throat,
having no more than .3700" length of parallel-sided freebore, .3755" in diameter, with a 1.5-degree leade into the rifling.
Something like that.

Overall average of about 200 fps advantage goes to the WBY, at equal pressures of .375 H&H, with various bullets.

DRG says: Kiss my grits.