Magnum primers

[ncbengal]

Small pistol magnum primers are, I assume, "hotter" than regular primers. Having used a few in some .357 mag. cases, I wonder if there is a "compensation factor" that might make them okay in .38 spl cases. Any authoritative data or intelligent opinions out there? I am not about to push the limits of my Mod. 19. Thanks.

 

[Reloader Fred]

I'm assuming you're asking this question because you haven't been able to find standard primers to load .38 Special with. Primers are beginning to show up, so it shouldn't be long before you'll be able to buy them again.

With that said, the difference between standard primers and magnum primers is in the priming compound, as you surmised. High speed photographs of the flames from both types of primers show the magnum primer to have a longer and hotter flame during the detonation.

You can use magnum primers in .38 Special, but you have to work up your load the same as changing any other component. Start low and work up.

Hope this helps.

Fred

 

[valkyriekl]

I've heard that you should drop your powder charge by a little bit (10%?) to compensate for the hotter primers, but they'll probably do just fine with regular .38SPL loads, and guarantee a more complete burn.

 

[PDL]

When I first started reloading, I loaded quite a bit of .38 special using Mag small pistol primers without any trouble. But as the above posts mention, you've got to back off the loads and work up. 10% seems to be the common recomendation. Do not take this to be a recommendation, but seems to me I had 4.3 gr Bullseye and 150gr jacketed HPs with the MSP primers. Snappy but no obvious pressure signs or problems. That was also 20 years ago, so things have changed I'm sure.

Start low and work up, like any other component change.

 

[ncbengal]

Thanks, guys! I have a decent supply of reg. primers, but also got a good price on a 1000 of the mags, and don't imagine I would want to shoot that many mag loads. I have a good 38 target load with 158 gr lead swc's and 4 gr of w231. I'll back that down to about 3.5 gr and check primers after firing for signs of pressure. Then, since I'm having trouble finding w231 locally, I may do a new search.

 

[Skip Sackett]

There is another difference in those primers. I believe it is either in cup material or thickness. I know some folks that have had problems with getting them to light off in "tuned actions".

Also, they are designed to work at higher pressures.

The cautions are valid and reasonable. You sound like you are on the right track. Have fun and be safe!

 

[Jack Flash]

Since it's a Model 19, and you are going to be working up loads anyway, is there any reason you don't work up some light-to-midrange loads in .357 cases? And if you don't already have some powder that manuals recommend a mag primer for, you could use this as an excuse to buy some.

I was just reading something Brian Pearce said along the lines that he likes to use .357 Mag cases in his .357s, .44 mag cases in his .44 Mags, and .454 Casull cases in his ... well, you get the idea. I prefer to do that too. Midrange loads are about all I load any more.

 

[bnewc75]

38spl target loads

I have used mag primers in low end target loads with no issues.... start low build up.... be safe

 

[ArchAngelCD]

Thanks, guys! I have a decent supply of reg. primers, but also got a good price on a 1000 of the mags, and don't imagine I would want to shoot that many mag loads. I have a good 38 target load with 158 gr lead swc's and 4 gr of w231. I'll back that down to about 3.5 gr and check primers after firing for signs of pressure. Then, since I'm having trouble finding w231 locally, I may do a new search.

Dropping your 4.0gr load 10% would change it to 3.6gr. I've found to develop the same velocity when using a Magnum primer instead of a standard primer you only need to drop the charge .1gr to .2gr. You should chrono your 4.0gr W231 load and then chrono the ones using a Magnum primer and you will see a charge of 3.9gr with the Magnum primer will duplicate the 4.0gr load with a standard primer. Of course you should work up like said above but I'm sure you will get those results. (I also charge 4.0gr W231 under a 158gr LSWC, my favorite .38 Special load)