Making the 357 magnum great again

[megasupermagnum]

Warning, the following is not to be considered load data. Use at your own risk.

Of course it was always great, but it sure seems to have lost its luster to some people. What was once a powerhouse, is now considered marginal for hunting even medium size game. While some blame the rather weak loads often found on shelves, there are plenty of full power ammo out there that I can't believe this is the whole reason.

I'd like to begin by saying that while I like to load to potential, I chose to take this project on for a practical reason. My S&W model 57 with 4" barrel is a great handgun. I love the way it handles and shoots, and the custom Jordan trooper grip is top shelf. While it is a great shooter, it is still very big to carry every day. The GP100 on the other hand, I can carry all day, and even conceal it.

My model 57 also suffered from the same problem as many N frames, in that heavy recoiling loads will cause the cylinder to rotate backwards. I have since put in an extra power cylinder stop spring from Wolff, so for all I know this problem is far reduced. Before I did, I had problems with 240 grain bullets, mostly when shooting one handed. I resolved to stick to lighter bullets, which is fine by me. I came up with the 220 grain bullet, that is now sold by Arsenal molds. It is a sweet shooter. The handgun is touchy on which loads it shoots good, but it really likes this bullet with 11 grains of 800x, for about 1150 fps.

One day while talking about how I wish there was a 41 magnum GP100, someone had asked how much more it would be than a 357 magnum. While bullets would be limited to .360" nose's, I think bullets up to 275 grains would be very practical in such a gun. Then I got to thinking, why not try to match my model 57 load in a 357 magnum?

So I designed the following bullet with Mountain molds, which is my first from them. He makes a great mold. It is a 220 grain WFN, that drops at .360" and 220 grains lubed when cast of my alloy. The nose flat is .300", exactly the same as the 41 magnum bullet. The nose length is .360", the maximum that will fit in a GP100. It is gas checked, with a short shank, and lube grooves with a gentle angle. This provides the most compact bullet possible.

My first few attempts at the range were pitiful. Groups were all over the place. Often I would get 3 or 4 close, then a shot 2 feet out. The flier was usually oblong, obviously they were barely stabilizing sometimes. Oddly I found the slower loads shot better. Lighter loads with bluedot, which couldn't be going but 800 or 900 fps often shot about 6" at 50 yards, and the surprising part is they were quiet. I decided I could either trim the mold down to 200 grains, or shoot them faster. I had worked up H110 loads to max loads listed for the 215 grain SWC, but the unburned powder tells me that maybe I did not go high enough. I may try H110 again in the future. I noticed there was plenty of powder room left for H110, and though to myself that a slightly slower powder might be a good choice. I decided that 300-MP might be a good choice. I worked up slowly, and found similar results. Then at 14.5 grains, things instantly worked. Just like a light switch, it was shooting very serviceable 4" or so groups at 50 yards. I worked up to 15.5 grains, which shot 3 3/4", and called it good. I never had any pressure signs in any of my testing.

Today I chronographed 15 and 15.5 grain loads. The gun is my 5" barrel Ruger GP100. I was using Federal brass with Federal 100 standard pistol primers. 15 grains went 1131 fps average, with 74 fps extreme spread. 15.5 grains went 1195 fps average, and 42 fps extreme spread.

Wowza, that is some horsepower in a small package. I have successfully matched my 41 magnum load for sure. It is not all roses, but I don't expect it to be. The model 57 is still slightly more accurate, and I'm sure that will be more true the longer the range. Recoil in the GP100 is not that bad, but the 57 is definitely more pleasant to shoot. I'm happy anyway, I met my goal, and I got to shoot more.

[mattw]

You are a man after my own heart! I shoot the LBT 230 grain OWC in my 657, darn good bullet with a bunch of H110 behind it. I was never able to get the matching LBT 357 bullet, I would take that 357 mould and widen the nose a tiny bit more and take 10 grains off of it and call it good. I have played with the Lyman 215 grain .358 bullet, but have not had much success with it, was really designed for the 357 max.

[megasupermagnum]

I've tried the Lyman 215 gr SWC in 357 maximum, and 357 magnum. It does work really well in the maximum. It seemed to shoot fine for me in the magnum, but it takes up so much powder space. Besides the velocity thing, some brass bulged due to the base seating so deep, and would not chamber. I never did try it in 38 special, but oddly 38 special brass did not seem to have the bulging problem. I've heard good things about it in the special, so maybe I should give it a go.

There is obviously more to stabilization than simple RPM and formulas. The fact that the slower loads seemed to stabilize fine is odd. Many seem to like the 230 grain thunderhead for bowling pin shooting, and they only shoot them as fast as they have to, 800ish fps it seems. For whatever reason, this 220 grain bullet I designed here is balanced in such a way that it seems to hate the 1000-1100 fps range. I'm no engineer, and do not pretend to know why.

I do think 200 grains is a good area for the magnum. It offers a good combination of speed and weight, and likely produces the highest momentum vs 180 and 220 grain bullets. As I said, I set out to meet a specific goal, so that determined how I made this bullet. Have you shot the OWC bullets at longer ranges, say 150+ yards?

[35remington]

Transonic velocities combined with some bullet shapes are always potentially suspect. I have a little problem with minor comet tails on otherwise well stabilized 25-20 bullets in that velocity range. It is not enough to make them shoot poorly but does not occur below or above that speed. This is a rather fast twist barrel of 1-10. Bullet weight and shape approximate the RCBS 85 FN. Aerodynamics along with velocity are playing their role I suspect.

[charlie b]

Yep, some bullets will do funny things in the transonic range. Has to do with how and where the shock waves attach to the bullet And sometimes a shock wave will move a bit which has really interesting effects.

[shooting on a shoestring]

I believe your GP100 has a twist of 18.75”.
Might try that load in a Blackhawk with 16” twist.

[megasupermagnum]

I believe your GP100 has a twist of 18.75”.
Might try that load in a Blackhawk with 16” twist.

That is a good idea. I didn't realize the twists were different. My dad has a stainless blackhawk with 4 5/8" barrel. It is an older model, just after they came out with the transfer bar. I'll try them in that, and see what happens.

[Kosh75287]

My shooting hand is SIMILARLY designed in such a way as that IT doesn't tolerate 220 gr. at ~1100 f/s from a K or L-frame revolver very well, either.
I have a Ruger Police Service Six that I'll match against any similarly sized .357 for strength, and have fired some horrendous loads out of it. But I'd rather fire a 171 gr Keith SWC at 1360 f/s (chronographed) from it, than a 230 gr. at 950 (which is probably possible).
The PHYSICS of the 2 loads involved suggest that the heavier slug produces less recoil. Fine. But 230 gr. at 950 f/s in a 1911A1, reciprocating "shock absorber" and all, is STILL a handful. The same load, in a platform that weighs 14% less, and in which nothing reciprocates, sounds uninviting in the extreme.

[megasupermagnum]

I'll agree with you. I often find the lighter and faster loads are more enjoyable to shoot. In 45 acp I've loaded a 255gr at 850 fps... and it is a handful in my Sig P220, although well in my comfort range. It should only have about 8.5 lb of recoil force. My own 357 Keith bullet load is only going 1225 fps, although I have loaded them to about 1380 fps in this gun. At 1225 fps, the 175 gr bullet should have 10.6 lb of recoil force. Yet shooting the two side by side, it's no comparison, the 357 magnum is much easier to shoot.

The above mentioned load, 220 gr at just about 1200 fps is a handful. It is essentially a mid range 41 magnum load in a GP100. It feels very similar to a lower end load in my 44 magnum Redhawk, the 250 gr Keith at 1225 fps.

[megasupermagnum]

After looking through Ruger's website, I wonder if their twist rate isn't an error. As far as I can tell, every other 357 magnum from Ruger at the moment including the LCR, SP101, Blackhawk, and Vaquaro are all 1:16" twist. They do list 1:18.75" for the GP100, but I find it strange they would use an odd twist for only a single model.

[shooting on a shoestring]

It’s my understanding the Blackhawk was button rifled originally and that 16” twist was a common 35 caliber button. It was right between Colt’s 14” twist and S&W’s 18.75” twist, so Ruger went with it. Maybe he also thought the Blackhawk was more apt to be shot as a hunting gun with heavier boolits?

I think the GP100’s are broach rifled. I suppose the choice of 18.75” twist could also be related to common tooling or the thought the DA revolver would be shooting lighter boolits shorter distances.

Who knows? Probably Outpost75...