request review .375H&H -> .375 Weatherby game plan

[rp85]

good afternoon;

• .375H&H -> .375 Weatherby game plan request review.
• Shooting nothing but cast bullets.
• Game plan to fire form 375H&H brass, new and once fired, to 375 Weatherby.
• Mix of new and once fired .375H&H cases.
• Will anneal all cases before loading, trim all cases then start fire forming .375H&H cases.
• Trim all cases to 2.835” (based on shortest case in lot)
• Cast bullets are Lyman 375449 gas check cast bullet\Lee 375250
• Sized to .378", barrel 377” (slugged barrel)
• 15 grains of Red Dot powder.
• With .375 Weatherby case, OAL of loaded round is 3.235. length needed to close bolt.

Using Weatherby 375H&H brass, Lyman 375449 gas check cast bullet with 33 grains of IMR4198, used small tiff of Dacron before seating bullet, 50 yards group size .348”, shooting bench and sand bags. Speed unknown, 26.5” barrel unknown manufacture. Rifle weights 10+ lbs.

Thx for any input.

rp

[RobS]

May think about a tuft of Dacron filler on top of the 4198 powder before seating the bullet. Makes for more consistent ignition of powder which makes for better groups.

[rp85]

did use a small tiff of Dacron, my error for not including in info provided. thanks for your reply.

[725]

Some time ago I loaded my buddy's .375 H&H w/ 13.5 unique and a cast boolit. Very accurate and suitable for deer hunting. Too many years ago to remember all the details. Dacron not needed.

[wwmartin]

Lyman 375449 over 17.5gr SR-4756. Is my practice load.

Bill

[wmitty]

So you are allowing the belt to control headspace on the cartridge. This should work if the chamber is reamed correctly and your brass is spot on dimension wise. Why not expand one piece of brass to slightly over size in the neck and then run it into the full length weatherby die to see where the bolt closes/ shoulder of case touches the end of chamber. By decreasing the expanded cases length at the shoulder in small increments until the bolt closes you can at least get an idea on your headspace. If the belt gives you acceptable headspace, great. If not, you might save stretching the cases by checking them…

[GBertolet]

For 375 H&H, 26 gr 4759, Lyman 375449 of enriched WW alloy, sized .378, with a tuft of dacron. 1625 fps. I use a Lee collet neck sizer. Brass seems to last forever.

[lar45]

We need a picture of your rifle.
Great caliber BTW.
I would fireform, then trim to length. I stead of trimming twice.
Does your 15gn Reddot give you a full fireform?
If you want to avoid case stretching, you could seat the bullets long enough to engage the rifling, while still being able to close the bolt.
That way the case will be held to the rear while the shoulder blows out forward...

[rp85]

good afternoon;

update. thx for replies.

Shooting only gas checked cast bullets from an arsenal mold, 375449 clone using Weatherby and Federal cases. Also using Forster’s hollow point kit for all bullets loaded.

Settled on two loads, 15 grains Red Dot and 35 grains of IMR 3031. Able to get higher speeds but not as accurate.

15 grains for Red Dot will fire form Federal case to the same dimensions as 375 Weatherby cases. Speed is 1400 fps but don’t know if this speed fast enough to expand the hollow point. Accuracy is very good, most of the time less than 1”.

35 grains of IMR 3031 will shoot way better than 1” groups at 100 yards with Weatherby cases. Using Federal case groups are a little above 1”. Strange part is the groups are left to right @ 1.5” apart from each other.

Able to increase bullets speed by 130 fps with IMR 4198 but rifle starts talking to me, recoil.

Wish I knew who made the barrel, all I know it 50+ ears old, 26.5” long and the OD of barrel is .665”.

Thx again for replies

rp