Home Forums Hunting & Shooting Handguns 357 magnum reloading question

I started reloading five or so years ago and have loaded and shot thousands of of 357mag loads with the majority being low/med velocity 158gr lswc rounds using w231/hp38.

I also loaded and shot a 100+ rounds with 6.5 grains of hp38 using a 158gr hornady XTP and a Win SPM primer (middle of the range load according to the Hogdon data). All of these were shot in a Ruger Blackhawk and I even killed a few small feral pigs with this load.

I moved last fall and just got my reloading gear setup and decided to load up the remaining XTP bullets I had.

I checked my manuals and for the first time noticed that the starting load for HP38 (6.2gr) has a cup of 33,700 and the max load (6.9gr) has a 40,000 cup.

Isn't the max cup for the 357 magnum 35k?

I just assumed that the published loads would be okay as long as I stayed under the max.

These will be used in a ruger sp101, security six or a Rossi m92 lever rifle...what are your thoughts on shooting these rounds in the above mentioned firearms?

Thanks,
Mike

I think it was higher at one time.

Hi Mike,

I'd go with a different powder. When I load for the .357 Mag, I use H-110. Were I to go with reduced loads, I'd probably go with Unique. But then again, I'd probably go with a 158 grain SWCHP .38 Special +P.

Maybe this source might be of help.

.357's MAP these days is 35K psi which is not the same as 35K CUP. I understand it was lowered some years ago at S&W's request in order to increase the service life of M19's and other K Frames.

I recently bought a new 357 and am doing load development for it. I've been using HS-6 for mid range loads in several pistols and it works very well for that application. I've been using 9.5 grains under a 140 Rem jacket as a plinking round for the past couple weeks. I'm buying 180's and will try HS-6 in them to see how it performs. If I can get ~ 1000 ft/sec from my 4" barrel, I'll likely be done.

I agree with using 231 for your light loads but try W 296 and a magnum primer for your heavy loads. I have had great luck with 296 and the XTP for deer hunting.

I am always going to be a fan of SR4756 for heavy loads in the .357 Mag.

I have pretty much settled on Unique for light loads and 2400 for heavy loads in everything from the .357 to the .45 Colt.

Ive been using HP38. 4grns in .38 mod 67, 6grns .357 in a sp101,and Rossi lever.

Ditto!

2400 is my powder of choice for full power .357 Mag loads. Less finicky and better load factor than H110/W296.

It's been hard to find Unique for the last 10 months but I scored 2 lbs yesterday at my lgs. Unique works great for medium loads in my S&W 686+. It' my favorite powder for .380 Auto and .45 ACP. Great load density and performance.

Dittos on Unique, but I find H-110 gives me better accuracy and more consistent velocity with top end magnum loads.

No. The max CUP is 45K. The max PSI is 35K.

H110 or Win 296 is the Premier Powders in the 357 Magnum with 158 gr XTP or Gold Dot bullets.

I like 10 gr of power pistol under a 125 gr Barnes, a hot powder it is but I think it gives less flash than 20+ grs of H-110/296.

All of those firearms are strong and will handle the pressure, but with so many much better powder choices for full power loads, I personally wouldn't consider using HP-38 for anything but under 15k psi target loads. H110/4227/2400 for the serious loads.

Thanks for the replies - looks like my loads are safe but I would be better off going with a different powder.

I've been looking for 110/296 or 2400 for months locally with no success.

Thanks for the clarification on cup vs. psi - I thought that was the case but not sure.

H110 just lights up your target for another shot if needed

YUP, keep whirling that cylinder and she'll keep the lights on.