"Magnum" Primers for .38 SPC?

[average_shooter]

Stupid question I'm sure at one point I knew the answer to.

Long story short, I've ended up with a glut of Magnum Small Pistol primers and only about 1,000 Standard SP left for my .38 reloads. What effects could loading .38's with Magnum primers have on burn rates, pressures, velocities, etc? If it matters I load with HP-38 as my primary .38 powder.

Longer version; I haven't been able to reload most of the year, just getting back to it. I went to Cabela's the other day (excessively long drive to get there, probably won't go again in the future) and thought it was Magnum primers I was short on so I bought a box, but when I went to put them in the supply cupboard I realized I got it backwards.

I just don't shoot that much .357, don't even have much brass for it, and the loading I do for .357 lately is black powder. So I've got something around 4,000 Magnum SP primers now. And very few Standards. Crap.

What do the reloading gurus on THR say?

 

[kingmt]

You don't need Magnum primers for ether. Just load the same & go shoot. I bet you can't tell the difference.

 

[MtnCreek]

I'm no guru, but I’ll throw in my 2 cents. I've loaded several cartridges with mag primers where standard primers are called for. In many cases, I've found the mag primers to perform better. The loads that I've sub'ed the mag primers used powder charges that used a good bit of the case capacity. It's been awhile since I loaded any .38's; but I believe HP38 only fills about 1/3 of the case. With a powder that seems to ignite easily and a lot of powder surface area exposed to the initial blast of the primer, that would raise detonation concerns in my mind. (never seen it happen, but heard it’s possible). In your case, I would use standard primers for the HP38 loads and use the mag primers for .357 or HV .38 loads with a slower, ball powder.

 

[cfullgraf]

Not the end of the world.

If your 38 Special loads are mid range or less, then magnum primers can be interchanged without issue. You might load a few to check first if you are concerned and to put your mind at ease.

If your loads are approaching maximum levels, you need to reduce your powder charge and work the loads back up.

 

[kingmt]

Your not going to get a book load 38 to be over pressure in a 357. If something goes wrong it wasn't the primer.

 

[average_shooter]

Good points all.

I guess I'm not worried so much about grenading the revolver, more about relative consistency. I load my .38's in bulk on a progressive press and dump them straight into a surplus ammo can. Not looking for uber-accurate target loads, just plinking fare. But if they're going to run different enough, I don't want to mix them in the same can of loose ammo.

So I was just curious if anyone thought the Mag. primers might make them run hotter enough to effect POI or maybe that they'd push too fast and not get as much of the powder burned, leaving me with excess unburned powder gumming up the works.

I'm just going to start loading them, maybe do a test batch to verify, but then just keep my Standard and Magnum .38's separate somehow.

 

[CZ57]

There are some cases where a magnum primer is recommended with .38 Special. One case that comes to mind is when using HS-6. Others are when using slower propellants in the .38 Sp.

 

[J2FLAN]

Back during the "Big Primer Shortage" all I could get was the mag. primers, I used them for about a year (thousands of rounds) 148gr DEWC over 2.7grs BE , I could not notice any differance out of my 4" K frame.

 

[cfullgraf]

So I was just curious if anyone thought the Mag. primers might make them run hotter enough to effect POI or maybe that they'd push too fast and not get as much of the powder burned, leaving me with excess unburned powder gumming up the works.

I'm just going to start loading them, maybe do a test batch to verify, but then just keep my Standard and Magnum .38's separate somehow.

I doubt that you would see a difference with mid range or lower loads in the 38 Special.

But doing a test is the best way to determine.

I also have used magnum primers in place of standard primers during primer shortage. I don't see a difference in point of aim, but I am no bullseye shooter either.

 

[gamestalker]

I've never tried magnum primer's for a standard primer application, but I have done the opposite with very noticable and negative effects. I tried both standard large rifle primers for a magnum appication with RL22, 7mm RM, and standard small pistol primers for a magnum application, H110 for .357 loads. Both went bang, but produced a lot of unburned / partially burned powder, and velocity and accuracy was all over the place.

But I would imagine if your careful and work the first few up with the right approach, starting on the low side, they might do pretty well, maybe even better than a standard primer because of the more than ample ignotion they'll produce?

 

[average_shooter]

... they might do pretty well, maybe even better than a standard primer because of the more than ample ignotion they'll produce?

Yeah. In my mind, the theory I have is that if there's a difference then it will be one of two opposite things happening.

Either the mag. primer compound burns hotter producing better, more reliable ignition; or it burns fast enough to decrease ignition reliability by driving the powder down the barrel before it all ignites.

The more I think about it, trying to recall shooting my standard reloads a few months back, I think there were some minor instances of unburned granules of powder left behind. So I'm leaning towards the idea that mag. primers will be more reliable, if anything, for my loads.

I should be able to make some time to run up some test batches this weekend and hopefully get out to the property to shoot them next week. If anyone else is interested I'm willing to update this thread with my results. But again, right now I'm guessing like others have stated that there will be little to no noticeable difference.

I've got some new BP .357 Mag. loads to test, too. Should be a fun range day.

 

[Deavis]

What powder and charges? If you are shooting them out of a 357Mag revolver, no worries. +P 38SPL rated revolver, no problem. Max charge in an old hand me down... consider dropping your charges.

 

[average_shooter]

I'll have to look at my data sheet tomorrow, but I'm not worried. Loads will be fired from a modern .357 Mag. revolver.

I don't remember exactly what load I'm using off the top of my head, but it's on the very low end to low-mid range. They're not as powderpuff as the factory Remington .38 SPC, but nowhere near +P either.

 

[TonyT]

Several years ago I picked up a 1000 SP magnum primers by mistake and did not realize it until I had loaded half of them in some mild 40 S&W loads - 180 gr. jacketed at 800 fps. WEhen I chronographed those loads against simialr load with the standard primer the velocity difference was ca 10 to 20 fps - virtually unmeasureable.
If you are shooting mild loads of 38 SPecial I would use the magnum primers. I would not use them in maximum loads where the standard primer was the nrom.

 

[d'Artagnan]

I just did a test to quantify the difference when using standard versus magnum primers in 38+P and 357 magnum loads. In Winchester 38 Special cases, with 158-gr Suter's Choice LSWC, 5.0-gr Unique, the Winchester standard primers gave muzzle velocity (mv) of 880fps, with Winchester magnum primers mv=904fps, a 24fps gain. In Winchester 357 Magnum cases, 158-gr Berry's plated HP, 7.0-gr Unique, standard primers got mv=1048, with magnum primers mv=1038; a 10fps decline! When I mentioned this to a reloader friend of mine he replied "Welcome to the wonderful world of reloading."

 

[evan price]

In the gun and loads you are describing, it won't make enough difference in plinking ammo to notice. Drop your powder charge by a tenth of a grain if you want to compensate but other than that the Magnums work just fine. You will have powder lot-to-lot variances- even in canister powder- that will have the same effect.
I've found that Magnum primers used in applications that don't normally require them had no real difference...but I don't load right to max.