cast boolits in .375 JDJ

[Jim22]

Yesterday I loaded up some test ammo for my .375 JDJ rifle. Using Lee's 250 grain flat point plain base boolit that casts out at 240 grains with 90-5-5 alloy. Started with H335 and Ramshot X-Terminator. 35.0 grains up to 37.0 in half grain increments. I will try other powders as well. Want to try IMR 3031 but don't have enough. Have been poring over powder burning rate tables.
Does anyone have any experience with this cartridge/bullet in a rifle? It may be a while before I can try them out. It snowed again this morning.

[Ed K]

No, not a lot of experience with cast in a rifle but looking into cast for my pistol. As you consider powder burn rates, note that the SSK recommended powder is AA2520.

[Screwbolts]

I do not have any experience with your cartridge or boolit. I do have great experiences with both X-terminator and 2520 with cast.

I find X-terminator works extremely well with cast in 308 with cast. Very similar charges and crony FPS speeds as compared to Re7 I have used it for boolitz of 150 gr to 218 gr cast in the 308 case. Fine accuracy and clean burning.

2520 works very well for me in 30/30 w/ cast.

I hope this helps.

Ken

[Jim22]

Thanks much for the input. I am not trying to hot rod these boolits. As stated before I would like a load that achieves 2,000 fps from my 27" barrel. The boolits are pretty hard and carry a gas check. Lubed with Carnauba Red. Today I rolled out some more test loads. Same boolit but with IMR 4198 and some old Reloder 7. Both starting at 33.0 grs. and moving up half grain at a time to 35.0. We are having unusually warm weather. Daytime temps in low 40's. If it holds for a few more days I may be able to get out the chronograph. We'll see.

If I can find some AA 2520 I'll try it.

Thanks again.

[quilbilly]

If memory serves, the 375 JDJ is based on the 444 Marlin. I have no experience with your caliber but I have gotten excellent results with 240 to 310 gr. cast in 444 with 5744, 4198, Red Dot (low velocity fun loads), and 3031. Getting more 2520 might be an issue recently with that recall notice on the powder. RE-7 should work well.

[catboat]

Fwiw, I think the 375 JDJ is a very interesting cartridge. Wish Marlin would have made a factory offering with it. Who knows, may the new owner, Ruger, will do it.

[missionary5155]

Good morning
We shoot a 405 JES (.412 groove with tapered 444 Marlin brass) which is not much different except you have a shoulder and probably a bit ore powder space.
4198 is the best powder we found with our cast up to 2200 fps with 265 grainers. We tumble PC our cast (ACWW) and have had good accuracy (under 3" at 100) with 265 to 300 grainers. We have a "stopper" load with a 345 grain FNGC but it not stable past 65-70 yards using 4198.
Barrel is only 20" also. Your 27" of tube would open the door to those slower powders. 4198 gets consumed real fast with 265 grainers even in a 20"tube.

[lar45]

Which rifle do you have?
I always thought that it would make a great levergun.

[405grain]

The case capacity, bullet selection, velocity, etc. for the 375 JDJ are so close as to be almost interchangeable with the 9.5x57 Mannlicher-Schoenaur, (375 rimless nitro express). Unfortunately there's not much cast bullet data out there for that cartridge either. IMR-4895 or H4895 might be good powders to consider. Can't offer any definitive information for a while - just got the 9.5x57 chambering reamer today so it will be some time before I can do any load development.

[missionary5155]

Good morning Lar45
A Marlin 336 that was bought with a rusty bore 30-30. Got the 405 reamed out about 5 years back.. Just as soon as I saw JES had the reamer.
If I was not a happy caliber .41 shooter I would have to write it is not worth the extra $$$ for dies and if you would have to get molds. After 30+ years shooting 41 mag (rifle, revolver, TC) and 414 Supermag (same 3 ) and fewer years with the 405 Winchester and 401 Winchester we already had 41 molds.

[Jim22]

Which rifle do you have?
I always thought that it would make a great levergun.

My rifle is a Ruger #3 single shot that was originally in .45-70. The rifle in its former caliber was far too light. Kicked like crazy and I was not too recoil sensitive. At that time in Alaska I commonly hunted with a .338 Win Mag in a Sako rifle. I have also owned two rifles in .458 Win mag. and one in .416 Rem. The .45-70 Ruger needed more weight so when I rebarreled it I had a heavier contour barrel installed. Settled on a bbl length of 27" because the rifle then torned out to be similar in length to my Sako. I agree, the .375 JDJ would be excellent in Marlin's .444 lever rifle. Trouble was I had to send the barreled action to JD Jones at SSK for chambering. He had a copyright. id a nice job, thought. The caliber designation is nicely hand engraved on the barrel.

[BJK]

I never even thought of casting for my .375 (.375/06 JDJ). Thanks for tugging on my brain to get it's attention. Jacketed bullets are quite expensive to shoot it very much, but keeping velocity down and casting them, that's doable.

[Jim22]

I never even thought of casting for my .375 (.375/06 JDJ). Thanks for tugging on my brain to get it's attention. Jacketed bullets are quite expensive to shoot it very much, but keeping velocity down and casting them, that's doable.

Thank you! The larger bullet diameter should give me, and you, all we need. The JDJ I have has a powder capacity a little less than the '06 case but a bit more than the .308. My testing in the past with Jacketed boolits showed me I could get 2650 fps with Seirra's 250 gr spitzer boat tail I'm sure the long barrel was a factor. Velocities like that are right on the heels of the 375 H&H. I no longer live in Alaska so no longer need that kind of power. Cast boolits should/will do anything I need to do.

[nelsonted1]

I have a .376 Steyr in a Steyr Forester. I am in love with the rifle and caliber. Too bad it is well on its way to near extinction. I can load it up to the point one can feel your world hesitate for a second or two or down to about 2,000 fps which is very managable. I could reduce it a bunch more except I went with the minimum load in the Hornady manual which worked so well I didn't bother changing it. I use 3031 or 860 surplus machine gun powder with 3 grains of 3031 on the primer.
I had a large buck jumping a fence into a property that disallowed hunting. I got the shot off hoping to keep him on my side of the fence. He seemed to have had a rope dragging him back and throwing him to the ground. I was so amazed I lowered the rifle and stood there with my mouth open. Then, the bitter neighbor showed up and began berating me hoping to find a dead deer on his side of the fence. Luckily, my rifle saved my day.

Ted

[405grain]

Other 375 JDJ cast loads - straight from the internet! I've been gathering 375 JDJ cast load information because, as I said earlier, that cartridge and the 9.5x57 are practically twins. None of these loads have been tested by me and like any load data from the interweb I would look at them with a jaundiced eye. First load: TC Encore rifle, Lyman # 375449, OAL 2.916", 20.0 grains of 4759, 1450 fps, 10 shop group 1.25" Second load, (same rifle, boolit and OAL), 26.0 grains of IMR-4198, 1550 fps, 10 shot group 1.25" Third load: (rifle unknown) RCBS 37-250-FN, 39.0 grains of H-4895, 1950 fps, 1.5 MOA. Other powders that were mentioned as possibilities for 375 JDJ are Varget and Reloader 15.
Remember, this is just untested info from random dudes on the internet, and you should work up your own loads with caution. Almost every source says that if you try to push cast boolits in this caliber up to 2300 fps or beyond, accuracy goes out the window. At velocity much above 2200 fps expect 3.5 MOA at the minimum, and minute of basketball more likely.

[PositiveCaster]

Accurate lists several suitable powders for jacketed bullets, including 2015, 2230, 2495 and 2520. Hornady lists H322, H4895 etc. There are lots of suitable powders for medium and full power loads, not so much for low power loads. Starting loads for listed powders would be a good place to start.

Years ago I helped a fellow Alaskan silhouette shooter with some cast loads for his Contender - because I had several .375 moulds. With the RCBS 37-250FNGC bullet we used around 44 grains of H4895. I don’t remember the velocity, but it was very accurate in his pistol. Hornady shows that load under a 270-grain bullet should produce about 1700 fps in a 14” barrel. I would guess that with the cast bullet it should approximate factory .375 WCF velocity in the OP’s strong rifle - the slower powder should make better use of his long 27” barrel. Not sure how his bullet will hold up to that velocity due to potential leading. Size and alloy matter there.






.

[Jim22]

Thank you both, Nelosnted1 and 405grain, and positive caster. I have printed the internet load data. It's interesting. Because of the cast boolits I have been concentrating on faster burning powders like IMR 4198, Reloder 7, H335, and Ramset XTerminator. Been kind of bummed because it's so hard to find other powders but I have some Varget and Reloder15. I understand that pushing the cast boolits too fast can ruin accuracy. That's why I have a self-imposed limit of 2,000 fps. The bullets I have been casting are Lee's 250 flat base. I want a bullet with a gas check so I ordered a mould from Midway but it's on backorder. It's an RCBS two cavity 37-250-GC. It has a nice meplat. Already have some gas checks.

[lar45]

You could probably get whatever you need from Accurate molds.
I just picked up the 38-295B for my 375 Ruger. I have test loads loaded, just haven't tried them yet.

[Jim22]

That is a really good looking bullet. Looks like a bore riding nose with two and a half lube grooves. I say half because my experience with gas checks is that the shank for them is usually longer than the depth of the gas check leaving about half a groove to contain lube. Good size meplat. Should be a winner.

[missionary5155]

Good afternoon
Is the 375-06 and the 375 JDJ the same beast ?
If they are near equals we have several JES bored 375-06 (near Whelens). We shoot 250 grainers for plinkers A FN 270 grainer PC'd for all around hunter, a 300 grain FN PC'd if ever going bear hunting and a 325 FN PC'd for a stopper if ever needed.
Really a fine cartridge that produces about 85%+ what you would want from the 375 H&H which we also shoot.