Magnum primers/loads for .357

[ReeferMac]

I recently acquired a 4" S&W 686 in .357.

I have everything I need to reload 9 mm (press, dies, standard primers, boolits, titegroup powder), and have been doing so for a couple years. I bought some used reloading gear from a co-worker, and now have dies for .357/.38 (older, but in good shape).

The used gear I bought came with some magnum primers and older powder the previous owner used for 357 mag loads. Handful of cast boolits, too. 

- Is it necessary to use magnum primers or can I use standard small pistol primers?

- can titegroup (or other standard issue modern reloading powder) be used or do you HAVE to use a Magnum powder? I get that I may need a more powerful powder to achieve the pressures required for SAAMI 357 mag loads, but I don't have a chrono or anything, so... Just reloading pkinking ammo, really. 

 

Anything different reloading 357 mag vs. 9mm? I have a recipe for my 124 gr round nose 9mm I'm happy with (4.2 grains titegroup), but starting from scratch on the 357. Was going to try 4.5 grains titegroup and work up from there?

[RED333]

I use Titegroup in all my pistol loads, from 25ACP up to 45 Colt with 357, 38, 44 in between. To me shooting is shooting, be it mild loads to hot loads. The difference is the wear and tear on me and my pistols. As far as primers, I use standard for general loads and save my mag primers for mag loads.

[Hozzie]

Buy yourself at least one reloading manual.  Not that this group isn't well established, but taking load data without some sort of reference to check is asking for trouble.  There are all kinds of powder/primer combo's you can use, but spend $20 and just read and start to peruse loadings.  You will learn something and be a lot safer about it.  It concerns me when anyone says I was going to try something based on a completely different round.   

Edited January 17, 2022 by Hozzie

[Clutch80]

Many, if not all, powder manufacturers have online load data so you can check there if you don't have a manual.  I do recommend having the manual though.  I load a pretty good amount of 357 mag and only use magnum primers if the manual calls for them.  Most of the loads in the Lee manual do not.

[ReeferMac]

What's the difference between a regular and magnum primer? Admittedly I don't know. Just more of the good stuff inside to ensure a big boom on the main charge?

[gary_boom]

Don’t know the difference between primers but I use regular primers for magnum primers. Can’t tell the difference.

[gregintenn]

Basically, powder for a magnum cartridge is slower burning, thus more difficult to ignite. Magnum primers are supposed to be hotter to help ensure reliable ignition of such powder.

I would also strongly recommend buying a reloading manual or three, and adhering to published data.

The 357 Magnum is a very versatile round. You can load anything from light target loads to large game hunting loads.

I would recommend using the magnum primers with powders such as 2400 and H110, and regular primers for light loads using powders like Unique, Bullseye, and the like.

The 357 magnum is simply a lengthened 38 Special cartridge. Folks were hotrodding the 38 in guns like the 38-44 N frame Smith and Wessons. While these loads worked in that big, strong revolver, it proved too much for many lesser guns. The new 357 was too long for the 38s chamber, and helped prevent these hot loads being fired in weaker revolvers.

The main difference in loading for this and the 9mm is crimping. An auto cartridge headspaces on the mouth of the cartridge, so you basically just remove the bell from the case mouth. Most 38 sp bullets will have a crimp groove. This cartridge headspaces on the rim, so you can roll crimp the case mouth into the crimping groove. Other than that, it’s the same…size/deprime, bell, prime, powder, bullet, crimp.

 

Edited January 17, 2022 by gregintenn

[Alleycat72]

Quick load is your friend. Mag primers have a thicker cup and will handle more pressure. There is some debate as far as hotter or longer duration flame. It depends on who you ask sometimes. I will leave it at that. 

[Hozzie]

Quick Load is great if you want to really know pressures, estimated velocities, etc.  I use it when I am loading CF accuracy loads or if I am trying out different powders.  For the guy who just wants to load some "target" rounds, a good reloading manual (or 3 as Greg says) is all you need.  I suspect many of us have 4,5 or 10 laying around for cross referencing.

[Jamie Jackson]

Great advice already.

I too only use magnum primers  for H110 and 2400 as Greg mentioned.

I have some good .357 loads using AA#2, Unique, and Bullseye I tend to keep my 158 gr bullets at or just below 1000 fps.

I also load 9mm using mag primers from time to time and just reduce the powder charge a bit.

@ReeferMac As a matter of fact I'll be heading out to ORSA this week to chrono some loads. You are always welcome. IMHO a chronograph, along with a good manual, are some of the best handloading investments a person could make.

Alliant, as well as most powders manufactures, offer solid handloading data on their websites. Tech support at Alliant is excellent and they've helped me work up some loads they don't even list. Good people IMO.

Just PM or email me if I can be of assist.

Jamie

[ReeferMac]

Thanks for the offer Jamie, I haven't been up there in a few years. 

If the snow ever breaks I'll probably have to go to work! 

[Alleycat72]

I mean honestly, I'll send you a manual. I haven't used them in years. You can get on Hodgdon's web page and get the information for free.

[Alleycat72]

https://www.hodgdonreloading.com/reloading-data-center

[Jamie Jackson]

1 hour ago, ReeferMac said:

Thanks for the offer Jamie, I haven't been up there in a few years. 

If the snow ever breaks I'll probably have to go to work! 

You're welcome.

I recall you don't go up there anymore, but I have to do the 23 mile drive to get my chrono work done. sigh

The offer stands if I can be of assist.

[JustEd]

On 1/17/2022 at 11:10 AM, ReeferMac said:

What's the difference between a regular and magnum primer? Admittedly I don't know. Just more of the good stuff inside to ensure a big boom on the main charge?

From what I have read they are the same except for a slightly thicker/stronger case material.  As far as magnum being hotter that is rather hard to prove, primer manufacturers are pretty tight lipped about specs.

For now just use what you have.  I have loaded very hot .357's with regular sp primers and I quit before the primers did (ouch).

[JustEd]

On 1/17/2022 at 3:03 PM, Jamie Jackson said:

Great advice already.

 

I have some good .357 loads using AA#2, Unique, and Bullseye I tend to keep my 158 gr bullets at or just below 1000 fps.

Jamie

That is a really mild load.  You must are shooting softer lead???

 

btw I also belong to ORSA,  Usually go to Gattlinburg Sportsmans Club for pistol or any Chrono work as there is less "traffic". Its also. lot closer to me

[gregintenn]

1 hour ago, JustEd said:

From what I have read they are the same except for a slightly thicker/stronger case material.  As far as magnum being hotter that is rather hard to prove, primer manufacturers are pretty tight lipped about specs.

For now just use what you have.  I have loaded very hot .357's with regular sp primers and I quit before the primers did (ouch).

Load the same load, one with a magnum primer and one wit a regular primer and shoot them over a chronograph. That should somewhat answer your question.

[Jamie Jackson]

24 minutes ago, gregintenn said:

Load the same load, one with a magnum primer and one wit a regular primer and shoot them over a chronograph. That should somewhat answer your question.

I did just this on Jan 12th.

I loaded some 158 gr LSWC Hi Tek coated bullets (Hoosier's) for my LCR snubby in .38 spl.

The powder was 3.6 gr AA#2.

Winchester Magnum small pistol primers gave me an average of 693 fps

Winchester Standard small pistol primers gave me an average of 649 fps.

I've found AA#2 easy to ignite and certainly the magnum primers were for a "let's what happens" situation. No signs of a pressure spike, primers looked fine, and I couldn't appreciate a difference in felt recoil.

I've loaded 10 k plus of 9mm using Magnum primers during the supply crunch after Newtown. I just initially dropped my charge around 10% and worked to my desired fps. Again, no issues.

 

I do try to keep magnum primers on hand for powders like H110 for .357 mag loads as recommended. But I've certainly run it and 2400 using standard small pistol primers.

I just checked my notes from 1993. I had a 686 at that time with lighter than factory springs (they are factory now) but those springs wouldn't set off (according to my notes) CCI magnum primers under a load of 16 gr H110. I switched over to Winchester standard small pistol primers and they ran fine. (Note, I didn't own a chrono in '93.)

 

Yes @JustEd, those 1000 fps .357 loads are nice and mild. And I'm using the .38/.357 158 gr bullets I mentioned earlier. They listed as 14-16 BHN and are sized at .358. I like them. I'm abused myself and my guns enough over the years, so this is a pleasant .357 load to shoot.

 

[chances R]

good video out on reg primer vs magnum......basically no significant differences.  Included rifle primers too.

 

[JustEd]

I think Reefer was basically asking if it is safe or if significantly better performance can be obtained with magnum vs reg small pistol primers in .357 handloads

just to recap my opinion is that regular primers work just fine but I can understand where one might want the assurance of a stronger base material when approaching higher pressure loads*  Considering primer availability, I would just load away and as always work up your load.  Meaning watching the cases for bulging or primer deformation as you go from a starting load to a more powerful one.

There is quite a bit about magnum vs regular primers on the internet. I tend to trust people who do their own testing rather than those just regurgitate opinion.

Here is another interesting read:   https://loaddata.com/Article/BenchTopics/Magnum-Primers-for-Standard-Pistol-Loads/331

*I have no proof of this, but suspect that historically part of the reason for a stronger case material in 357, 41, 44 magnum loads was the inconsistency in firing pin strike between different manufacturers revolvers. I have seen punctured primers in a couple of revolvers (long long time ago) with factory magnum ammo. Yep, I think they were poorly made ones  As I remember one was a single action chambered in .357, not American made.

So have fun man and happy shootin’