Forcing cone friendly 125g 357 mag loads?

[Silvercreek Farmer]

Usually shoot 158g 38+p loads out of my 3” SP101, (thousands of them with no sign of forcing cone erosion) but they other day I fired a few of my 357 rifle loads, Lee 120 TC over a near max load of Red Dot or Promo. The result was a very entertaining report and bit of a fireball without too much recoil. I’d like to shoot some more of these, and 50-100 rounds a session is routine. I know 125g and heavy loads of 296/110 are hard on the forcing cone. I’ve read the problems with 296/110 have to do with the pressure curve peaking as the bullet base passes into the forcing cone. How about the faster powders? I’ve got some Herco and Power Pistol I might try for a bit more fireball. Got some Blue Dot and 2400 as well, but recoil might start to surpass the fun level for 50-100 rounds.

[Sig]

I'm not gonna be a lot of help as far as load data but I know I've read in multiple places that Alliant has withdrawn all 357mag, 125 grain bullet, Bluedot data. Had to due with high pressure.

[Silvercreek Farmer]

I'm not gonna be a lot of help as far as load data but I know I've read in multiple places that Alliant has withdrawn all 357mag, 125 grain bullet, Bluedot data. Had to due with high pressure.

Thanks, I am aware of that.

[Sgt H]

I don't shoot a lot of jacketed rounds in .38/357 mostly cast. A load I have used for a long time in 357 is 9 grains of Unique under a 125 grain JHP. Runs about 1275 fps from a 4" and is pleasant to shoot. The original full power 125 grain loads from Federal and Remington were 1400+ and not fun to shoot even in a 4" K frame. While not up to the full power loads, the Unique load is far more than a 38+P. Can't report on forcing cone erosion as I haven't shot enough of them for it to be an issue. I would think a similar load could be worked up with Power Pistol or Herco. I would suspect forcing cone erosion would not be an issue with the faster powders as the pressure both peaks quicker and drops off faster. Just my $.02.

[Rapier]

I usually just go to 231 with the 125 cast. 231 does not care, 38 or 357 case, same load. Makes things simple to load 357 cases in a 357 gun.

[fredj338]

I doubt you could damage the fc on a sp101. The issue with max slow powder loads with 125 is the flame cutting as the bullet passes the gap, powder is still burning hot. With faster powders, I would bet powder is burned before it hits the cyl gap..

[rintinglen]

No reason not to use your Promo/Red Dot in your SP 101, but if you need to use it, Power Pistol will get you some place close to where you want to be. 6.0 grains in 38 cases, 9.0 grains on .357 cases for a little extra oomph with your 120 grain boolits. Red Dot is more economical, but if you need to dance with the one you brought, PP will do.

[MT Gianni]

If you shoot 1000 rounds the 20 gr difference between 125 gr bullets and 158 gr is about three lbs of alloy. I don't find that significant and make sure that my use of the 125 gr bullets in 38 special are medium speed, fun loads only. 357's don't get loaded with less than 155 gr bullets.

[AlaskaMike]

I've been trying some loads like this myself. With a 125ish grain bullet I will never use powders like 2400 or H110/296. They're just too slow and if anything will result in forcing cone erosion it would involve a load with slow burning powders and light bullets.

For me, I've been working up loads using 231, BE86, Power Pistol, and Accurate #5 and #7. So far Power Pistol and #7 seem to be the winners in my S&W model 28, and Ruger Security Six.

[DougGuy]

A load I have used for a long time in 357 is 9 grains of Unique under a 125 grain JHP.


How about the faster powders? I’ve got some Herco and Power Pistol I might try for a bit more fireball.

Herco is pretty close to Unique in burn rate, takes about 10% more to match Unique in pressure and velocity, I am sure there is load data for it in 357.

[charlie b]

I also used slightly faster powders with 125gn max loads. A bit less muzzle flash. Any of the book loads have worked for me.

And, yes, in the SP101 you get a sharp recoil bite vs the heavy push and muzzle flip of the 158s. From the 4" Colt with Hogue grips they are almost pleasant to shoot.

A while ago I narrowed things down and now use 140gn bullets in the .357

[Jack Stanley]

I'm not certain , but wouldn't single base powders be less apt to erode ??

Jack

[jonp]

I've shoot several thousand Promo low end 125gr and 142-148gr target loads through various 38sp and 357Mag pistols with no problems.

I'm no shrinking violet recoil wise but full house 357Mag loads out of my SP101 snub created enough fireballs and recoil that I sold it. That gun sure could take it with no problems but my wrist could not.

[Silvercreek Farmer]

Loaded 9.5g of Power Pistol behind the Lee 120 TC, (10.5 is max for 125 Jacketed). Nice satisfying boom and very tolerable recoil. Chronoed around 1250 fps. Not far off factory loads listed on Ballistics by the Inch. Didn’t see too much flash, but it was broad daylight. I’ll have to try again at dusk. Didn’t shoot for groups, but I connected with the steel about as often as usual. Forcing cone was much cleaner than usual, no black soot, just clean steel, probably sand blasted clean!