Does anyone have loads they would like to share? I have worked through all my reference books and now am looking for "real-life" loads. Any responses will be welcomed.
Thanks.

Roger,
Good to see you back. Been workin or playin too hard to post lately?
My favorite load was always 88 or 89 grains of IMR 4350 with the 300 grainers. Gave 2700 to 2750 fps with most bullets.
The .375 RUM has nothing significant on this oldie goldie load. And of course you can fire .375 H&H factory loads in the WBY if your ammo is lost.
Pushing 270 grainers at 2900 fps and 250 grainers at 3000 fps is also supposed to be possible. I always stuck with the 300's.

I'll bet RL15 would work well with the lighter bullets. I will have to try that some day.

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Good huntin' and shootin',
RAB

Roger,

I have had my best results with the following components for 375 Weatherby 300 grain loads:

- Winchester brass - not Federal or Remington
- Federal 215 or 215M primers
- Hodgdon H-4350 powder - Start at 82.0 grains. Firing three-shot groups move up in 0.5 grain increments until you find an accurate, safe load for your rifle.

With a 26 inch barrel I have been able to obtain velocities over 2,820 fps.

Good Hunting !

Just in case anyone is interested, I just visited Weatherby's web site a few days ago, and they have re-introduced the 375 Wby. . They have for sale on the web site, loaded ammo and brass. And they are chambering a few of their Mk V rifles for it.

Gentlemen,
Thank you for your replies. Frank Wells, the gunsmith in Tuscon who was doing the rechambering of my ZKK-602 ran into difficulties with three reamers having different dimensions, one 0.048" short, 0.078" long and the correct one. It ended with him declaring he hadn't seen a foul up like this in all his years of 'smithing even on less well known cartridges, which is saying something.

It started when I fired my first cartridge, it had an extra shoulder so it looked to have been chambered short. I then was able to purchase around 80 cartridge cases of original Weatherby .375! I sent him a couple and he ordered a new reamer which came in 0.078" long (these are all base to beginning of shoulder measurements). In the mean time I had traded 3 original cases to a collector in Nebraska for a whole box of early Norma .375 H&H brass that had been fireformed in a .375 Weatherby chamber (not original Weatherby), guess how long these cases were? Yup, ~0.078" long. So using the two reamers and setting the barrel back one turn Frank was able to match the dimensions in the A-Square reloading manual. I used this as a reference because my two main reference books; The Handloaders Manual of Cartridge Conversions by Donnelly and Designing And Forming Custom Cartridges by Howell have different specs. To make sure I was on the right track with the specs in the A-Square book I called Weatherby and carefully explained the problem to an engineer in the engineering department. He told me since (at that time) the cartridge was being tested by SAAMI he couldn't give me any info at all on it, he would tell me that, "according to the dimensions you read to me the re-released .375 Weatherby will have no problems chambering in your rifle". Ok so he told me it was the same cartridge. Either was I have a fine rifle that I have fired around 15 rounds through.

Everything finally came together just as finals were starting at UAF so I had around an hour to zoom out to the range and pop some caps to see what it was like. I like it. I was doing my fireforming using 235 grain Speers with 78 grains of IMR-4350, Winchester brass and CCI-250 primers. I couldn't find Winchester primers in Fairbanks. They pop out perfect. Using the same load with 300 grain Sierra Spitzers is quite different than my .500 A-Square which is the only other large rifle I have. The .500 is a huge PUSH while the .375 is a strong JAB. I liked the difference. I don't know how much my rifle weighs, I think it is around 9 pounds or so.

I had thought of using H-4831sc and try to get 2725-2750 with my 25.1" barrel. I will use some H-4350 and see how it works. Ackley's books all show IMR-4350 as THE powder but we have more choices these days. I am looking forward to the powder companies coming out with loadings.
Ron and Pumba thanks again for your replies and David, wouldn't you know I had decided on this chambering and sent my barrelled action to Wells to only find out some days later Weatherby was bringing the .375 back. So much for my "I just want to have something different" rifle".