Magnum primers in non-magnum loads

[David LaPell]

Right now given the shortage of primers, I was going through some of my stash and found that a couple years back I had gotten some large rifle Magnum primers (CCI) back when I was looking into magnum loads. I don't have any of those larger calibers now (.50-70 doesn't really count) but it's getting so eventually I will be down to those primers eventually until the costs come down which doesn't look like it will be in the near future. So my question is, who has used magnum primers in non-magnum loads? Mostly what I load these days are .30-30, .32-40, .38-55 and my .50-70 with 7.62 x 54mm bringing up the rear. All with smokeless powder. I don't load of them very hot, closer to the minimum load than the max in every round I shoot.

[anothernewb]

From what I understand. mag primers are basically a hotter flame. Although I will clearly state that I am basing that on little more than observations from pictures, and could be missing much information. Perhaps slightly harder cups in some circumstances as well. There was a test (I think in 223 cases) where they tested pretty much all brands of primers for small rifle and compared the results.

That being said - I see no reason mag primers could not be substituted. some will say to drop a few grains or tenths of powder and work back up to make sure you don't get overpressure. and I understand the the safety aspect of that. I also find myself looking at it from the standpoint of - if your burning all your powder in your charge, how can it possibly create more pressure than you already have? Perhaps the hotter primer could ignite the powder faster than the non mag version, but were talking some pretty short spans of time. Unless you are running on the ragged edge of case capacity and pressure - would could create issues - I think the average person, who is loading much under the maximums, will notice little to no difference in the loads between mag and non mag primers. However, a theoretical change in burning rate and characteristics could result in a change of POI vs POA the same way it can change with any loading alterations.

That being said - safety first, is never a bad position to take.

[downzero]

I use magnum primers when I use ball powders in rifles. That includes in 223, 308, and 30-06. I have not loaded the cartridges you are loading here so I'm not sure if ball powders exist for them, but if so, the books almost universally require magnum primers ("ball" powder is a Winchester trademark, but by this, I mean all spherical rifle powders, of which I use several). I use magnum primers in 223 even with stick/extruded powders because the thicker cup is safer in rifles with floating firing pins and all of my rifles have them. Other than that, I would use magnum primers in cartridges where they weren't required in a pinch, but conventional wisdom is that they may not produce the same accuracy as a non magnum primer (and of course there's a risk of higher peak pressure if they light the powder faster, which you can address by working up the load again).

If you're going for extreme accuracy at distance, you might be disappointed, but otherwise, they should do the job just fine, as long as you follow normal safe reloading practices regarding load development.

[earlmck]

The magnum primer will probably give slightly more pressure/velocity with any given powder charge than your standard primer. With mild loads this isn't going to kick them into danger category. If you really want to be totally equivalent my first guess (if I didn't have a chronograph to check it out) would be to reduce powder charge by a half grain.

I shoot a fair amount of 5744 with cast loads and my usual practice is to use a CCI magnum primer, which my chrono has shown makes for more consistent velocities with this powder.

[farmbif]

if I have them I try to use mag primers with ball powders, even if not ball powder, work up new load to know exactly what you're getting.
that's my suggestion anyway

[Conditor22]

The gun gurus say to back the load off 5-10% when switching from plain to mag primers.

I'm in the same boat, somehow I have 3 bricks of LRMP.

I'm trying to trade them for primers I use on a local gun forum before I develop new loads with them.

[John Boy]

Magnum primers are primarily used for ball and stick powders

[dale2242]

I did a small test to see the difference in a load using LRM primers in 45ACP.
My standard load is a mild load of 700X in the 45ACP with a 200 gr SWC bullet.
I have no way of testing pressure but the mag primer loads were 50fps faster than the standard LP primers.
Other than that I saw no difference.

[Rich/WIS]

I use MRP with Win 748 and BLC2. When using those powders with standard primers and shooting with electronic muffs frequently could hear the firing pin fall and then bang. With MRP there was no delay.

[WALLNUTT]

In the past at least Winchester produced rifle primers that are suitable for std or mag loads per printing on the box. I doubt they used std primers for mag loads, so I'm thinking they are mag primers.

[white eagle]

I use SRM in my 6.5 Creedmoor loads
no problems at all

[bangerjim]

I back off the load of ANY powder recommendation about 5-7% when using mag primers in standard loads.

Works for me. With any pistol or rifle powder I have tried. And I do not know (or care) about the change in velocity.


Just be glad you have the mag primers!!!!!!! Some guys cannot find any!



banger

[just bill]

I too have the same question on another post. A couple years ago there were a series of posts about the same thing , I believe that a 10% reduction in the powder was the popular response, however there are those that say there is nothing wrong with using them interchangeably, of course be careful near max loads.

[Led]

To me it depends how hot the load already was. If it's a target load I do not hesitate to use standard or mag interchangeably. If it's already hot, I'd back of 5-10 percent and work back up.

Later,
Stephen

[ragsflh]

i use them both ways.standard loads back down about 5 percent.

[Daekar]

I have used small rifle primers in 357 magnum loads without issue, and they performed like the small pistol magnum primers I substituted them for. Like others have said, I believe the generally accepted wisdom is, yes, you can do this without a problem most of the time, just work up your load again because you might see pressure changes.

[ktw]

While I have plenty of primers for the next few years, current inventory tends to be heavy on the Large Pistol Mag and a bit light on Large Rifle based on my current shooting activity. One of these days I'm going to try working up some cast boolit rifle loads using LPM primers in order to use them up, saving the regular LR primers for more traditional jacketed bullet loads.

Either that or start shooting a lot less 30-06/2400 through an 03 and a lot more 45 Colt/H110 through a Winchester 94.

-ktw

[Shawlerbrook]

Very common question these days. Reduce your load by 10% and stay away from max loads and shouldn’t have a problem.

[Texas by God]

I’ve used magnum large rifle primers for decades in various non magnum cartridges with both cast and jacketed bullets. Mainly because I have a lot of them and it helps me conserve my regular primers. As stated above, reduce your load and all’s well. I’ve always used them for ball powders in rifle cartridges; I’ve never used magnum primers in any handgun cartridge. My 30-30, 30-40, and 38-55 have all been loaded with cast bullets and LRM primers.

[Tortoise1]

I had the same question. Thanks for the info everyone!