Black Powder Loadings in 357 Magnum

[SPJackson]

I am curious about what performances are possible with loadings of 357 Mangum rounds with Black powder. I have found some conversations on this site before discussing it. I wanted to see if anyone here has experimented, or knows others who have, with BP in 357 rounds. I have a Winchester carbine and rifle and I'm curious how many grains would provide the farthest effective distance or most consistently accurate groupings of shots. I found that BuffaloArms does sell 357 cartridges loaded with BP, but it does not state how many grains. The consensus I have found so far is that 29-30 grains is the maximum amount that can be loaded, and 25 grains is what is recommended in some sources.

https://www.thehighroad.org/index.php?threads/powerful-black-powder-loads-for-357.795086/page-2

https://www.thehighroad.org/index.php?threads/ha-loaded-up-357-magnum-bp-cartridges.784916/page-2

https://castboolits.gunloads.com/sh...al-38-Smith-amp-Wesson-Special-B-P-Ballistics

 

[hawg]

Whatever load you decide on remember no airspace in a bp cartridge. If you want less than a max load use a filler. 25 grains is a .36 revolver load.

 

[LaneP]

In the mid 80's I loaded up a batch of 158gr LSWC and a case full of Pyrodex P and shot them out of my Ruger Security Six 2-3/4" bbl. They actually felt reasonably stout and the bullets buried themselves to the base or slightly deeper from about 10 feet when shot into an old utility pole I was using as a target. As mentioned, ensure you are using all the powder the case can hold while still allowing for some degree of compression. I always aim for at least 1/8".

 

[MEHavey]

See https://thefiringline.com/forums/showpost.php?p=6675236&postcount=18

Note 50-thou compression w/ 21 grains of 3Fg.
Makes me wonder how 50% more powder possible w/o effectively turning powder column into solid cake.

 

[Smokepole14]

It would definitely work but I don’t think you’ll get .357 magnum performance. Smokeless is a lot more powerful than the holy black. I do know that a .357 case level will hold around 27 grain of bp, but that’s without a bullet in the case. So a 25 grain charge with a 158 gr bullet would be very similar to a 44 cap and ball. With a 140 gr round ball and a 30-35 gr charge I would expect the cap and ball and the 357 to be very similar. Since you mentioned using a rifle I do imagine the velocity will increase and it would definitely do some damage to what ever is on the receiving end. Sounds like a fun experiment to me

 

[Ugly Sauce]

No, performance will be a little better than the .38 Long Colt cartridge. On compression, the more the better, "solid cake" or not. It will burn cleaner too. To get that much compression you will need to compress the powder in a separate step, which is worth the trouble. Using the bullet to compress the powder beyond "slightly" will result in very deformed bullets.

 

[Jim Watson]

Phil Sharpe reported 820 fps for .38 special 158 gr cast and 18 gr of King's Semi-Smokeless.
I have seen well over 900 fps given for black powder .45 Colt.
So I think you would get good stout .38 Special performance out of black powder .357.

I have seen a .357 Maximum BPCR being shot as far as 500 meters.

 

[J-Bar]

I shot literally thousands of black powder .357s in cowboy action matches. Hardly distinguishable from BP .38 Specials when using 2F granulation. I expect one would get a quite a bit more bounce if you use 4F compressed loads. I never did, and I am NOT encouraging anyone to do so. I expect an old model Ruger Vaquero or Blackhawk would handle them without blinking. But I would not expect ballistics to approach smokeless .357 loads.

 

[Ugly Sauce]

Just a wild guess, but I'm thinking around 800fps at best, maybe 850fps+ with a very compressed load, and Swiss 4fg powder, which would be up there with a .38special.

 

[Ugly Sauce]

I never did, and I am NOT encouraging anyone to do so.

I'm thinking that in a Winchester chambered for .357 Magnum, compressed 4fg is not going to come close to anything considered high pressure, even compared to .38 Special.

 

[J-Bar]

I'm thinking that in a Winchester chambered for .357 Magnum, compressed 4fg is not going to come close to anything considered high pressure, even compared to .38 Special.

I agree. Just trying to cover our six in case someone tries it in a defective gun.

 

[Ugly Sauce]

I agree. Just trying to cover our six in case someone tries it in a defective gun.

That's what I figured. I get it!!

 

[Seedy Character]

Haven't done .357, but I acquired a box of .431 round ball.

Filled .44Mag brass with 40 gr fffg.
Mild, smoky and fun. Lots of clean up.

Performance along the lines of .44Spl.
Accuracy was not stellar

 

[SPJackson]

I'm thinking that in a Winchester chambered for .357 Magnum, compressed 4fg is not going to come close to anything considered high pressure, even compared to .38 Special.

I assume you and others mentioning 38 Special rounds are talking about those loaded with smokeless powder. In this case right now I'm just concerned with blackpowder loads. I know that the original 38 Spec cartridge was loaded with a 158 grain bullet and 21.5 grains of BP. So I am hoping that a modern 357 can be loaded with more powder. So then my question is how many grains of BP, and what bullet mass and or shape, will provide the best performance in either max effective range or accuracy in shot groupings

See https://thefiringline.com/forums/showpost.php?p=6675236&postcount=18

Note 50-thou compression w/ 21 grains of 3Fg.
Makes me wonder how 50% more powder possible w/o effectively turning powder column into solid cake.

Thank you

 

[Ugly Sauce]

I assume you and others mentioning 38 Special rounds are talking about those loaded with smokeless powder. In this case right now I'm just concerned with blackpowder loads. I know that the original 38 Spec cartridge was loaded with a 158 grain bullet and 21.5 grains of BP. So I am hoping that a modern 357 can be loaded with more powder. So then my question is how many grains of BP, and what bullet mass and or shape, will provide the best performance in either max effective range or accuracy in shot groupings



Thank you

Yes, understood, making comparisons to a modern .38spl load, velocity wise.

I don't know if anyone can give you a ball park figure as to how many grains. A starting point might be to fill the case full, and then see how far you can compress it, (or fill it up to 1/16" short of the mouth of the case) and have enough room to seat a bullet. You may have to do that a few times to hit the "sweet spot". You should be able to pick the compressed powder back out of your case on your failures, if not, just shoot them off. Blanks. How many grains that would be depends on what granulation of powder you use, how much you can, or will compress it, and the length of the bullet you are using. And the case capacity of the specific brass you are using. So that does not enable anyone to throw out a specific grain weight.

What bullet will shoot best for you depends on your specific rifle, so no one can make a good guess there. Others can say of course, what has worked well in their rifles, which of course does not tell you what will work in your rifle or what length and shape will provide the best performance.. !!!

Heavily compressed BP loads can be extremely accurate. See photo below. That is 80 grains under a 400 grain bullet. And 100 yds.

 

[J-Bar]

The .357 Magnum case is only about 0.13” longer than the .38 Special (1.155 versus 1.29), not to increase powder capacity but to prevent chambering a .357 Magnum round in a .38 Special chamber. The little dab of additional space in a .357 case is insignificant when using black powder in either caliber. As has been discussed, you might be able to approach .38 Special smokeless +P ballistics by cramming a .357 Mag case with 4F powder. Maybe. But I don’t think you can get enough BP/substitute propellant into a .357 Mag case to duplicate smokeless magnum performance.

Have you chosen a bullet lubricant yet? That’s going to become an important consideration with increasing powder volumes, especially in a long rifle barrel. If the bullet runs out of lube before exiting the muzzle, accuracy will suffer.

 

[Ugly Sauce]

you might be able to approach .38 Special smokeless +P ballistics by cramming a .357 Mag case with 4F powder.

Yes, at best.

 

[Jim Watson]

I assume you and others mentioning 38 Special rounds are talking about those loaded with smokeless powder. In this case right now I'm just concerned with blackpowder loads. I know that the original 38 Spec cartridge was loaded with a 158 grain bullet and 21.5 grains of BP. So I am hoping that a modern 357 can be loaded with more powder. So then my question is how many grains of BP, and what bullet mass and or shape, will provide the best performance in either max effective range or accuracy in shot groupings

It depends on how much trouble you care to go to.
Pushing a small caliber BP repeater for range and power is not a common pursuit and it seems nobody here has done much in that area. I have not loaded for anything but single shots.

How many grains depends on how much compression you apply. In my single shots, Swiss needs very little compression for best accuracy. But Goex benefits from a lot of compression. Will you be limited to what you can do by seating a bullet without squashing it out of shape or will you use a die? Or a drop tube? Or both, as I do.

Will you load a bare bottomed bullet or over a wad? Or over a grease cookie? Lubrication is very important for black powder shooting and you will really need it in your repeater. I assume you will be shooting that lever action dirty, not stopping to wipe or blow your barrel.

I assume you will be loading from the magazine, so OAL is limited, therefore bullet length/weight. More bullet, less powder. Not a whale of a lot of choices there.

 

[Driftwood Johnson]

Howdy

This is not as complicated as you may think.

Believe it or not, 38 Special originated as a Black Powder cartridge in 1899.

That is why the cartridge looks so empty when loaded with Smokeless powder, because Black Powder is less energetic than most Smokeless powders, and more is required for a man-stopping load.

This is a page from a reproduction of the 1900 Smith and Wesson catalog.

Notice the load for 38 Special was 21.5 grains of Black Powder under a 158 grain bullet.

Bear in mind, these cartridges would have used the old Balloon Head cases, which had more powder capacity than modern Solid Head cases.






As stated previously, 357 Magnum is a little bit longer than 38 Special so it cannot be loaded in revolvers chambered for 38 Special. The extra length has nothing to do with stuffing in more Smokeless powder, there is still plenty of air space left in modern 357 Magnum ammunition loaded with Smokeless powder.

My rule of thumb for loading Black Powder into any cartridge is to stuff in enough so that when the bullet is seated, the powder will be compressed between 1/16" - 1/8".

That's all there is to it.

Determine where the bottom of your bullet will be when seated, and pour in a little bit more. Pour it out and weight it, that will be your optimum Black Powder load for that particular bullet.

I'm guessing around 22 grains or so.