.375 Weatherby Dialed In

[Nitroman]

A .375 Weatherby is probably not considered a long range rifle/cartridge combo, but I thought you guys might like to see what this ZKK-602 rechambered and built up by Jim Brockman can do.

That hole is exactly 1/2" side-to-side and top-to-bottom. Taking into consideration these bullets are 3/8" diameter, the center-to-center is roughly 3/16". I think that is pretty dang good.

The rifle with the Meopta Artemis 2x8x42mm:

The rifle will do this with the Barnes 300 gr. TSX but for some reason the brass will not hold proper neck tension. It is almost like the base of the bullet is larger than the rest of the shank, so the farther I seat them, the more loose they are. I am going to work on some GS Custom bullets in 265 and 300 gr. later this month.

I am going up to Kotlik, Alaska at the terminus of the Yukon River to look around for moose this coming Thursday morning. I think I may have a fun time.

 

[rifletuner]

Nice! Those CZs seem to be capable of very good shooting. I have seen some other custom CZ big bores that are very good shooters.

You may want to try a 250gn Barnes as a "light" bullet. I had them doing 2900fps in my 375 H&H. Took it to Africa with this load years ago and was very happy with the performance on game. I imagine you could get that load comfortably pushing 3000fps in the 375 WBY.

 

[Nitroman]

I am looking forward to working more with this round. The 2580 fps is the average of 12 rounds I chornographed. The pressure is an average of 53,125 psi, so not at all the max of 65kpsi of the Weatherby. I was conerned with getting the shots in the same hole. In the near future I may work up the velocity to see if I can still place them. I also want to stretch out way past 100 yards, but that is all the range here has.

 

[benchracer]

Excellent shooting and great post!

I know many people do not consider the .375 WBY or the .375 H&H to be long range cartridges. Loaded correctly, however, I believe they have potential.

I have a CZ in .375 H&H with a Meopta Artemis 1.5-6x42 that has the ranging/holdover reticle (4B?). Its accuracy has far exceeded my expectations from the first time I shot it. CZ makes a great rifle.

One advantage of the full size magnum action is the amount of room available in the magazine to seat bullets long. My rifle has shown promise with Hornady 300g BTSP's loaded to 3.750" over Hodgdon book loads of H4350. Top book loads were producing 2720fps at the muzzle. I still need to complete load development to see where my accuracy node is.

I also started experimenting with CE 300g MTH's. COAL with them was over 4". With the same Hodgdon book loads, they topped out at over 2760fps at the muzzle. If I can get some accuracy out of them, the .750 bc should turn my humble H&H into a legit ELR rifle.

If I can get the 300g CE's to shoot, I will step up to the CE 320's for their .830 bc. At $2 a trigger pull just for the bullets, though, I am looking for less expensive alternatives for practice. I have some 350g SMK's that I intend to try with RL-17. I may do the same with the 320 CE's as well. I am still keeping my fingers crossed and hoping for a Berger Hybrid in .375 that will stabilize in a 12 twist.

If my experiments work out, I will probably end up having to go with a second scope that is suited to ELR use. THEN, I will have to find a place to shoot that far.

Thank you for sharing your results. I look forward to reading about your moose hunting exploits!

 

[Mike 338]

Very nice. How long did it take to get your rifle back?

 

[Nitroman]

I had ordered a reamer from PT&G to be tight necked at 0.401", shortened freebore from 0.750" to 0.250" and the freebore diameter 0.3754". They incorrectly ground the neck diameter to 0.405" which is standard. I was quite upset until I fired a few rounds.

I can still load the Barnes and Sierra's out to touch the rifling if I want because of the short freebore, and they'll work in the magazine. I will find out how the GS Customs fit in the future.

I used Pressure Trace to keep an eye on things, this is the screenshot of this load I am using:

The first shot is a fireforming load using 78 grains H-4350 under a 235 grain Speer using Winchester H&H brass. I believe 3000fps is doable with the right powder and the 235/250 grain bullet. But it would sure make a mess on the receiving end.
Like I said, well below Weatherby max, just under H&H max. It works, so I have no desire to go up, maybe though just to see what the velocity would be at max. This brass is spendy though.
Interestingly the pressure with Winchester brass is around 5kpsi higher with the same load. I weighed a couple cases and they are 20 grains heavier. Hmmmm.

The total time Jim had the rifle was about 9 months. I know any good gunsmith could do the same, but Jim loves the ZKK/CZ's and it shows.

 

[Tikkamike]

Very nice! to solve your brass issue I would try annealing, im guessing the brass doesnt have enough spring back and as the bullet is starting its somewhat crooked and it bends that brass a little and doesnt come back. I think there is a good chance its a simple fix. I shoot the 270TSX in my 375 and dont have any issues.