Question regarding reloading for .357 Magnum rounds

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OldNewGuy

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Hey, all. Got a question about reloading for .357 Mag rounds. I've been building up my stock of brass, got the powder, got the LnL shell plate, got the dies, etc.

But I've been getting conflicting information on the need for Magnum primers for this caliber. About 1/2 my contacts say "yup, gotta have 'em" and the other 1/2 say "fuggedaboutit, you can use normal pistol primers, you don't need the Magnum primers"

Any practical input based on experience?

Thanks,

O.N.G.
 
Small rifle primers will work, in place of small pistol mag. I recommend federal as their cups are softer and work more reliably in "softer hitting" pistol firing systems.

I read an article in a magazine, hand loader iirc, the priming composition is exactly the same in small rifle and small pistol magnum primers. The cup is made a bit differently (rifle primers are harder to withstand higher pressures) so a hard CCI primer is not recommend in pistol loads.

That said, mag primers are only really needed when loading heavy charges in the magnum. Even then regular small pistol primers will work, in most loads, but you will see a drop in velocity. Not a big deal if you build your load around it.

After hand loading for 25+ yrs, I've learned a few things, read a lot of books and info on reloading. I don't always follow the rules......

I quite often use mag rifle primers in non-magnum rifle calibres for "cold weather" loads, especially when using powders that have a sensitivity to temperatures. Ie; I really like IMR 7828 in .243, but from 0 to -25 the velocity drops and groups open up. My go-to charge touched off with mag primers brings the velocity back up and groups tighten. There is no noticeable difference in performance from -30 all the way to +20.....

Cheers!
 
I've gone through about 500 sellior & ballot small primers. It says for rifle or pistol on the box. No issues yet. That's using Tightgroup and N340.
 
I think what it comes down to is that SPM primers are rarer than hen's teeth, even now that things have returned to something nearly resembling normal as far as reloading supplies are concerned. Having reloaded .357 for a couple of years now I would agree with the consensus: SP is fine for everything up to mid-level target loads. If you are going to go all out and load to max, then an SPM primer is a requirement, with the option of using a SR primer instead if you can't find SPM WITH THE CAVEAT that you should follow normal safe load development (start with a lower charge and work upwards, checking for signs of overpressure all the way) at all times. No substituting without proper development, period.
 
I find that it depends on what else you load.

I find I load some small primer loads (40sw, 9mm), but I load a lot of higher pressure loads (compressed 38super, 357 mag). That dictates me to buy more small rifle then small pistol, for lower costs in quantity.


Also availability of SR is usually better than SP
 
Thanks for all the feedback, guys. Lots to sort through, but I'm starting to think I really should trend towards Small Rifle or (hopefully/possibly/maybe-if-there-are-any) Small Magnum Pistol primers. A couple of the responses have left me reconsidering whether to move to a different powder as well (I had lots of Titegroup kicking around from my 9mm reloading, and saw Lyman did spec a Titegroup load for both .357 & 38 Spl) instead of just using what I already had.

Thanks again!

O.N.G.
 
I just started loading .357 and all I could find was spm primers, cci 550 to be exact, so far I have been using with H110 (recommends magnum primers), but also with Titegroup (which doesn't recommend magnums) and both have worked great, very happy with the results.
 
I recently re-loaded 50 x .357 magnum using S&B once fired casings, IMR-700X and winchester small pistol primer. It worked for me.

*Once fired cause I bought these new S&B 357 factory ammo, and I re-used the brass.
 
I only use may primers with slower ball powders like H110, enforcer and 2400. I have also been using SR lrimers with no noticeable change in performance.
 
where did you get this "Titegroup (which doesn't recommend magnums)"? From hodgdon, it says SPM for titegroup.

Chas59 said:
I just started loading .357 and all I could find was spm primers, cci 550 to be exact, so far I have been using with H110 (recommends magnum primers), but also with Titegroup (which doesn't recommend magnums) and both have worked great, very happy with the results.
Click to expand...
 
I use what ever I have . if I was worried my H110 is'nt going to get burnt properly then I would use Magnum primers . but I have used small rifle and small pistol and small magnum pistol primers without even worring . I just watch for signs of excess pressure . cratered primers or flattened out . I don't excede book specks and I stay alittle under . in over 30 years I have'nt had any issues.

lots of 357 loads .
 
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