Will I need a magnum primer for this .357 load?

[flip180]

I'm going to adjust my Lee carbide dies out from .38 SPCL to .357 after getting my .94 Winchester Trail's End. I was wondering if I can coninue to use my Winchester small pistol primers or do I need magnum primers stepping up to .357. I plan on using a 158gr. SWC, 4.5gr.-5.0gr. of titegroup, Remington brass and Winchester small pistol primers. This will just be a plinking load and that's it. I'm not looking for a barnstorming round for any specific purpose. I just want something to punch holes in paper and make some tin cans dance around at 50-100yrds. I don't really want to shoot .38 spcl through the gun due to Winchesters not being entierly reliable with .38's and the so called crud ring that can build up in the chammber using .38 SPCL's. Any input will be appreciated. Oh, and one more thing. How much crimp should I use. I've noticed that titegroup seems to be a bit sooty with my .38's but a stronger crimp could sort that out with this powder right?

Thanks, Flip.

 

[Jim Watson]

You do not need a magnum primer for Titegroup just because you are putting it in magnum brass.

I don't know if a harder crimp would make it burn cleaner. You have the stuff, give it a try.

 

[stans]

No magnum primers until you get to the slow burning powders like AA#9, W-296 and H-110.

You may find it necessary to bump up your powder charges about 0.5 grains over your 38 Special loads. It has been my experience that the longer magnum case takes just a tiny bit more powder to get back to 38 Special ballistics.

I recommend a medium roll crimp. A few years ago I experimented with light target loads in 357 magnum brass. Went from no crimp, to just a slight roll, to a medium roll, to full heavy roll crimp. I found that the most consistant ignition, velocity, and accuracy came from a medium roll crimp with light loads.

 

[TooTaxed]

You should use magnum primers for the .357 and standard primers for the .38-Spl. as recommended by the Lyman manual. I suppose you get more positive ignition in the larger case?

 

[stans]

Actually no, magnum primers have a hotter flame to ignite the slow burning powders. Fast and medium burning powders are easy to ignite and a magnum primer can upset their normal burning rates.

 

[alex-v.]

I do not remember why Lyman used the CCI 550 for the load development with the 357 Mag but for most powders the Standard primer will do the job.

Another thing to think about; the Lyman manuals do not list TiteGroup loads, but the Hodgdon manual does. And, the Hodgdon manual does list the Winchester SPM as the primer they used to develop the loads. If you call the tech people at Hodgdon you will probably be told that the magnum primer produced more consistent internal ballistics, especially with the light loads. And, the tech told me to go ahead and use the Standard primer if the results were satisfactory when loading with TiteGroup.

Even in tightly crimped loads in the 357 Mag TiteGroup is still smokey and a bit sooty. I figure I will be washing my hands anyways and cleaning the guns so what is a little extra if I like the load.

 

[flip180]

I looked on hodgdon's website last night and foung out the same thing about SPM's with titegroup. The reason that I ask is that I have about 1000 winchester SP primers paying aroung and don't want to waste them if I don't have to when swithing over to magnum cases.

Flip.

 

[junke]

Flip, I would be interested in hearing a range report when you start shooting your rifle. I recently purchased the same rifle and Love it! i first bought it as a plinker to compliment my GP100, and my wifes .38, but after shooting it i was amazed at the accuarcy. it shoots 2 to 2.5 inch groups with everything i shot through it. i have loaded some 180 Gr. XTP JHP with Mag primers and 16 grns of H110 and get 1.5 to 2" groups with it. so it went from a plinker to a hunting rifle. i carry my GP100 as my side arm. all the same ammo is sweet. im getting 1600 fps with that load. Im going to be loading up some 158 gr XTP shortly and hoping to get over 2000 fps. which is on par with a 30 30.

 

[The Bushmaster]

Not really Junkie. I wouldn't doubt your wizdom in using that rifle on small game, but a .30-30 uses a 150 gr bullet traveling at around 2100 to 2300 fps or a 170 gr traveling at around 2100 fps. Be careful and pick your target well. The .357 mag and the .30-30 have a much different impact capability. Shoot well and good hunting.

 

[BluesBear]

For over 30 years I have been listening to both sides of the argument about which primer to use in the .357 magnum.
Now most of the manuals and powder guides show magnum primers in their load charts. But as many other long time reloaders, I learned a long time ago that for 85% of the .357 magnum loads out there standard small pistol primers will work just fine.

I had the opportunity to ask an executive of a major powder/ammunition company about this about 20 years ago. What he said was that the average difference in muzzle velocity was about 15-20fps but that the magnum primers created a different pressure curve. There was a larger spike at the beginning of the burn.

So that by developing all of their load data around the use of magnum primers, if anyone were to substitute standard primers the slightly lower pressures would still be completely safe.

But if they had developed the data around the standard primers and the reloader substituted magnum primers, then pressures would be raised. Possibly into the danger zone.

And since a lot of people automatically assume that since the cartridge has the word Magnum in it's name then it must need a Magnum primer they decided to err on the side of caution.


If it were me, I would buy a single pack (100) of small pistol magnum primers of the same brand.
I would load 50 rounds of 4.5 gr of Titegroup in .357 mag brass. 25 with standard primers and 25 with magnum primers.
I'd also load 50 with 4.7gr (25 of each primer) and then another 50 with the 5.0gr load (once again 25 of each primer).

I use different coloured "Sharpie" markers abd draw a ring around my primers to signify different loads. I bought a package with about 10 different colours at Sam's club.

I'd shoot them all the same day and see which gave me the best accuracy.
If the standard primers yielded at least acceptable accuracy, or if they were the most accurate, I'd go ahead and use them.
However if there is a big difference in accuracy with the magnum primers, then I would switch.


After all, reloading is about what performs best for you.