Fieforming some 375 Improved brass

SJB358

Ballistician
Dec 24, 2006
32,381
2,999
It was nice yesterday and I decided to form up some cases in my 375. I put the 6x36 back on it so it was a good chance to zero it up a little and form up some cases.









I picked a mid load in Sierras manual using their 300 grain SBT with IMR4350 and CCI250’s.

First group



I adjusted the scope and shot the next three.



Pretty happy with it. The next three I shot were with the Magnetospeed strapped onto the rifle. They went 2409, 2405, and 2403. Pretty danged easy for just picking a load out of the book. The book said a standard 375 would go about 2500’ish with the same charge.

Anyhow, it’s a really accurate rifle for being another JES rebore. It’s a 1-10 twist as well. I have some 250 Sierras coming for a little load work.



Need a steel gong on my little range to practice some offhand with. Perfect practice with the fire form loads!
 
Excellent! That is a cool cartridge and NICE rifle. Is that $3.65 a box? That must be old.
 
Based on my experience with the 375 Bee, you should get higher velocities with RL-17, but H4350 is a solid performer too. With a 300 AB I can get almost 2700 fps in my rifle with H4350 and another 80 fps or so with RL-17.
 
AFG270":2i91lv4y said:
Excellent! That is a cool cartridge and NICE rifle. Is that $3.65 a box? That must be old.

Yeah, 3.65 a box. That was for unprimed brass. Still, free compared to today’s prices.

Johnly":2i91lv4y said:
Based on my experience with the 375 Bee, you should get higher velocities with RL-17, but H4350 is a solid performer too. With a 300 AB I can get almost 2700 fps in my rifle with H4350 and another 80 fps or so with RL-17.

I think 2700 is definitely quite doable but man, I don’t know what I need to hunt with them 300’s just yet. They are wonderfully accurate though. I bet they’d be something from the prone though :mrgreen:
 
Very cool Scotty. I suspect you lost some speed due to fire forming cases. Still some serious HP.

JD338
 
I guess the cool thing is I could always load up those and probably still hunt just about any animal walking I’d suspect. I’m not sure a 300 anything at 2400 will bounce off much and man, it’s accurate enough as well.
 
Scotty that is one good looking group for just picking out of the book. Unless you have a need for speed that is some serious thumping there as is. Nice rifle also. Dan.
 
Nice stuff Scotty and it shoots great. It's nice having those kicking big bore guns to have a little fun. :grin:
 
Excellent!

I've used 75 grains of H4350 (haven't shot IMR 4350 in quite a while) in my 375 H&H, with various 300 grain bullets. A bit above 2500 fps. The Sierra SPBT has proven accurate from my Ruger. The only game I ever shot with that bullet was an unfortunate rockchuck... ;)

Much as I like the 260 gr AccuBond, the 300 grain bullet seems to be the standard weight for 375 loads.

I'll be interested in your results with different powder charges, and also with the 250 grain Sierra. I've read that it's a very good bullet for elk.

Regards, Guy
 
They’re darned accurate. I almost had half a mind to load a bunch more and just run it as is. Probably just hunt deer with it anyhow and chances are they wouldn’t be too far either.

I should have to the 250’s soon though. They might be pretty fun as well. I have some 250 BBCs I’d like to see if I can make shoot to the same POI.
 
I shot a 375-358STA for years and shot those 250gr Sierras at 3080fps with 80grs of 4350. I killed quite a few elk with that gun.
 
Sweet! What was the original caliber, did the rifle end up a bit muzzle light for you?
 
preacher":2n20xawg said:
Sweet! What was the original caliber, did the rifle end up a bit muzzle light for you?

It was a 300 H&H that someone rechambered back in the day to Wby. I got it pretty cheap planning to use it for a build. Ended up shooting it and it was a dog but I'd already found another action to use for the build. Decided to let JES work it over to a 375 large enough to clean up the Wby chamber, so it became a 375 Improved.. Those old P64's had fairly heavy barrels so it feels quite nice as a 375. Their version of the 375's is quite alot heavier. Mine is a touch less than 9lbs scoped which is about right for carrying mostly.
 
Pretty cool stuff! Excellent groups first time out! Or anytime out far as that goes. (y)


SJB358":2aa54urp said:
I guess the cool thing is I could always load up those and probably still hunt just about any animal walking I’d suspect. I’m not sure a 300 anything at 2400 will bounce off much and man, it’s accurate enough as well.

:lol: Yeah I'd suspect your right. If it was me I'd run with what you got, when you already got more than you need.
 
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