Just had a 375 Weatherby built on a m70 express action with a 24" krieger tube. The 300 grain partition factory loads are cronographing at 2825fps. This seems pretty hot. To bad they don't offer a tougher bullet (A-Frames)for factory loads as I doubt I can duplicate these numbers with handloads. We will see!! This is my first "real" big bore and I can't wait to start developing loads and shooting it any sugestions?

You should try the 350g Woodleigh protected points. I think they would be awesome at 2500 fps plus!

Chuck

Interesting that you get the Ultramag velocitites with that Weatherby ammo. I chronographed some 340 Weatherby, 210 grain Partition, factory ammo at 3260 fps. This prompted me to pull one of the Partitions. I weighed 96 grains of powder out of that factory case. I tried pouring it back in the factory case and several grains wouldn't even fit, even with packing.

quote:

Originally posted by j stoviak:
Just had a 375 Weatherby built on a m70 express action with a 24" krieger tube. The 300 grain partition factory loads are cronographing at 2825fps. This seems pretty hot. To bad they don't offer a tougher bullet (A-Frames)for factory loads as I doubt I can duplicate these numbers with handloads. We will see!! This is my first "real" big bore and I can't wait to start developing loads and shooting it any sugestions?

Last time I sampled it, the Weatherby factory load was the 300-grain Nosler partition with 88.8 grains of unknown powder, in the one I pulled apart. It delivers just over 2740 fps in my 24" barrel.

You may have a tight barrel or throat.

Factory ballistics are 2800 fps in a 26" barrel, and the factory was very honest with that one.

You can easily duplicate the factory load with H4350 Extreme at about the same charge as the mystery powder.

Start low and work up.

It does seem fast for a 24 inch barrel. Does it have the Weatherby freebore? If not it is definetly a hot load .

Ken....

I like Chuck's suggestion. 350gr softs and solids at the 375Wby's pace would be very potent and very versitile too.

JPK

Sending you PM regarding Woodleigh bullets you may be intersted for your rifle.

quote:

Originally posted by Heat:
It does seem fast for a 24 inch barrel. Does it have the Weatherby freebore? If not it is definetly a hot load .

Ken....

The reamer is a proven reamer to the specs from Weatherby when the cartridge was reintroduced. So it does have the free bore. No signs of pressure with the factory load. Interestinly the data from norma lists n204 as almost the same charge within a couple of tenths of a grain for 300gr bullets in the 375 weatherby and 375 ultra mag. I am going to try n204, MRP and 4350 extreme.

congrats.

if you feel comfortable with the recoil, i would also go with 350gr woodleigh's
(SD .355!!)

quote:

The 300 grain partition factory loads are cronographing at 2825fps. This seems pretty hot.

Yep, that'd be Weatherby factory ammo! They load 'em hot from the factory to get the signature Wby performance. If you're not getting excessive pressure signs, you should be OK. When we shoot ours with factory ammo, it's not uncommon for the rim to have an extractor mark on it...

My .375 Weatherby with a 24" barrel gets just over 2800 with factory 300 grain ammo.

Why wouldn't the Nosler Partition be tough enough?