.375 H&H casting and powder choice.

[King David]

Good morning all.

My first post on this group. I’m David from South Africa and I’m looking for a powder to use for my cast 280gr gas checked bullets. I’ve done load development on our Somchem powders (South African) but after them blowing up the factory twice in two years I’m reluctant to use the powders and I’m looking for alternatives. We get all matter of the USA and European powders on our shores these days so I’ll appreciate your input.

Cheers David

[M-Tecs]

http://www.castpics.net/subsite2/ByCaliber/Cast%20in%20the%20375%20H_H.pdf

https://forum.castbulletassoc.org/thread/6715-375-h-h-cast-loads/

https://castboolits.gunloads.com/showthread.php?352360-Reduced-375-H-amp-H-loads

https://www.africahunting.com/threads/375-h-h-cast-bullet-info.23275/

https://loaddata.com/Cartridge/375-HH-Magnum-Cast-Bullet/3247

[414gates]

I used 4451 for a 245 grain paper patch.

64 grains for 2150 fps, 68 grains for 2310.

My notes don't say if I used dacron, if there was any air left I would have.

[Larry Gibson]

In my M70 three six bits (375 H&H) I use a 270 gr Lyman 375449. For practice and general shooting to 200 yards I cast them of 95/2.5/2.5 alloy and WQ out of the mould for a BHN of 18 +/-. I GC (Hornady) and lube (2500+ or NRA 50/50) at .377 and load them over 49 gr of 4895 and use a dacron filler. Velocity runs 2150 fps out of the 24" barrel with 1 1/2 to 2 moa accuracy. For short range practice (25 - 100 yards) I cast them of #2 alloy and WQ out of the mould for a BHN of 26 - 28. I load those over 4895 or 4350 fps to 2400 fps (55 - 60 gr w/dacron +/- depending on powder). Those give 2 -3 moa accuracy at 100 yards and recoil close to full power 300 gr jacketed loads for DG practice.

For offhand DG practice I put a paper plate at 50 yards then 6" bulls or similar similar size targets at 35, 20 and 5 yards general online from 50 to 5 yards. From the first shot at 50 yards I have then NLT 4 seconds to engage the other 3 targets from farthest to closest. Object is to hit all 4 targets in the 4 seconds (basically 4 seconds for 3 shots). A simple test to set up and challenging for quick accuracy and rifle manipulation.

299702

[Beaverhunter2]

Very interesting, Larry! I like your practice course idea! H4895 or IMR4895?

Thanks!

John

[skeettx]

60 grains of 4831
Mike

[15meter]

18 grains of Blue Dot under a bullet I'll have to check the next time I'm in the shed.

Just a fun dinger-ringer load. And at 18 grains, a pound of powder goes a long way.

[Rick R]

I’m shooting a cast boolit that drops at 280gr and after some development I reduced the load of Varget (ADI AR2208?) that I use with 300gr jacketed bullets by two grains and my Whitworth .375 purrs along quite nicely. It’s a peep sight only gun but I get 1” groups at 50 yards.

[Larry Gibson]

Very interesting, Larry! I like your practice course idea! H4895 or IMR4895?

Thanks!

John

Either one. Not anywhere near a max load pressure wise. The Dacron filler makes them both burn efficiently in the large case.

[gwpercle]

These 4 powders are listed in the Lyman Cast Manual #4 :
SR-4759
5744
4198
Rx 7

The following 7 powders are listed in Lyman Cast Manual #3 :
Red Dot
700X
Green Dot
Unique
Herco
SR-4759
Blue Dot

If you can get or have any of these powders I can post the data in the Lyman Manual for you .
Powder shortages are a pain ... but when the factory blows up ... twice ... what you gonna do !
Gary

[JonB_in_Glencoe]

I've used IMR7828

[Beaverhunter2]

Either one. Not anywhere near a max load pressure wise. The Dacron filler makes them both burn efficiently in the large case.

Thanks! This is on my list to work on.

John

[W.R.Buchanan]

In my M70 three six bits (375 H&H) I use a 270 gr Lyman 375449. For practice and general shooting to 200 yards I cast them of 95/2.5/2.5 alloy and WQ out of the mould for a BHN of 18 +/-. I GC (Hornady) and lube (2500+ or NRA 50/50) at .377 and load them over 49 gr of 4895 and use a dacron filler. Velocity runs 2150 fps out of the 24" barrel with 1 1/2 to 2 moa accuracy. For short range practice (25 - 100 yards) I cast them of #2 alloy and WQ out of the mould for a BHN of 26 - 28. I load those over 4895 or 4350 fps to 2400 fps (55 - 60 gr w/dacron +/- depending on powder). Those give 2 -3 moa accuracy at 100 yards and recoil close to full power 300 gr jacketed loads for DG practice.

For offhand DG practice I put a paper plate at 50 yards then 6" bulls or similar similar size targets at 35, 20 and 5 yards general online from 50 to 5 yards. From the first shot at 50 yards I have then NLT 4 seconds to engage the other 3 targets from farthest to closest. Object is to hit all 4 targets in the 4 seconds (basically 4 seconds for 3 shots). A simple test to set up and challenging for quick accuracy and rifle manipulation.

299702

Larry: Can you actually do it?

I can do 4 man sized targets at 15 yards in <3 seconds with my M500 pump gun, but those are a lot larger than 5" I can do it in 2 seconds with my A5. This is also shooting Buckshot and not Slugs which would require more time to pick up the target.

Doing 4 shots in 4 seconds with a bolt gun would be pretty challenging? I'm Impressed!

Randy

[Larry Gibson]

Larry: Can you actually do it?

I can do 4 man sized targets at 15 yards in <3 seconds with my M500 pump gun, but those are a lot larger than 5" I can do it in 2 seconds with my A5. This is also shooting Buckshot and not Slugs which would require more time to pick up the target.

Doing 4 shots in 4 seconds with a bolt gun would be pretty challenging? I'm Impressed!

Randy

Randy

Yes, I can do it. However, it is 3 shots in the 4 seconds. The scenario is such; M'bogo is at 50 yards. Your first shot, while it may be lethal, has convinced him you do, indeed, owe him money and it's time to collect!. M'bogo comes for you. The 4 second time begins at the shot because it would then take a maddened and determined M'bogo about the 4 seconds to get to you from 50 yards. Thus, at the 1st shot and you then have 4 seconds to work the bolt 3 times, chamber 3 rounds and hit the targets one each in descending order (the 6" targets which is about the frontal area below the boss). Great fun yet tasking. It requires proper manipulation of the bolt during and coming down out of recoil.

[W.R.Buchanan]

So you are "Riding the Recoil" I do similar with the Pump Guns, but my guns have Vang Comped barrels so they don't raise up as much under recoil. The Drills are 2 shots on two different targets from the ready in 1.6 seconds, 3 shots, in 2.1 seconds and 4 shots in 2.7

I have to try something similar to what you are doing with slugs from 50 yards back in. Fortunately I don't load my slugs up past about 1250 fps and 2000 Fps would be out of the question. Most "butt kicker slugs" are down around 1600 fps. I have a limited shelf life at those velocities. 1-2 rounds.

Randy

[15meter]

These 4 powders are listed in the Lyman Cast Manual #4 :
SR-4759
5744
4198
Rx 7

The following 7 powders are listed in Lyman Cast Manual #3 :
Red Dot
700X
Green Dot
Unique
Herco
SR-4759
Blue Dot

If you can get or have any of these powders I can post the data in the Lyman Manual for you .
Powder shortages are a pain ... but when the factory blows up ... twice ... what you gonna do !
Gary

And the Lyman #3 Manual is available as a free download.

I think that's where my Blue Dot load came from.

[wmitty]

If you are not adverse to duplex loads and have access to the surplus powders normally used in Browning 12.7 x 99 or the 20 mm Oerlikon rounds relatively inexpensive loads can be worked up with WC 860 or WC 872. A light charge of 4227 or 4198 with the remainder of the case filled with 860 works very well with the Lyman 378674 ( about 335 gr with the soft alloy I have).