I've often wondered, when fire-forming 375 Weatherby brass from 375 H&H cases, do you lose any cases to splitting? Also, if forced to hunt with the H&H cartridges in a rifle chambered for the Weatherby, do you lose a substantial amount of velocity due to case expansion?

Just wondering since, on the surface, it looks more and more like the 375 Weatherby incorporates the best of all worlds.

I have owned one 375Wby in the past and am having another built now. I truly believe it is the best of the "super" 375s. Cases are available now from Wby/Norma and I have purchased several boxes to use for hunting. When I wanted to fireform from H&H brass it always was 100% succesful, no split necks or other troubles. Shooting standard 375 ammo in the improved chamber will result in standard ballistics or very little less than that.

I've never had any problems with this in my 375 Wby either. It's a good way to practice, and if you mark down your sight settings, you can use H & H ammo in a pinch. - Dan

If I wanted more velocity than the H&H provides I would go to the .375 Weatherby also. 100 fps more with equal pressures. A fine round.

I used to fireform both 300 and 375 H&H's in Weatherby chambers with no splits, but never did check for velocity differences. ~~~Suluuq

Nickudu-
I think you will find the difference between these rounds is more like 200fps with equal pressures. When I owned my last one I tried to do some testing on this, by measuring head expansion. I used brass from the same box for both cartridges, just fireformed the Wby first and then started loading and measuring head expansion. When I reached top levels I was at 2550fps with the H&H and 2780fps with the Wby.