Small Rifle Primers vs. SR Magnum

[The Remnant]

Occasionally, we are seeing SR Magnum Primers available but not regular SR.

How much should one reduce the powder charge if using the Magnum instead of the regular?

 

[Nature Boy]

I’d treat it like any load. When you change a component run your load development again, and as always, start low and work.

Let us know what you observe. In the loads I’ve developed and in the calibers I shoot I have not seen much of a difference.

 

[BLACKFIN]

If you have a chrono start at the lowest published data and work up. If you don’t. Don’t pass the half way point between low and max charge. The magnum primer will spike the pressure a bit faster than regular primers.

 

[reddog81]

If you're pushing max loads I'd drop down some. If at or near start loads you probably won't ever notice. he most likely issue will probably be igniting the primer with the harder cup. Depending on the gun this may or may not be an issue.

How much I'd drop depends on the cartridge and loads I'd been using.

 

[JJFitch]

Here is the ultimate primer on "primers" it's a little long but everything you ever wanted to know is here!

https://www.sksboards.com/smf/index...6fb6135clb3k4&topic=56422.msg646510#msg646510

Magnum powders can be slow to "get going" and build the required pressure. The longer brisance (spark) makes it happen more efficiently. As mentioned above work loads up using standard reloading protocols!

Smiles

 

[ArchAngelCD]

Reduce .1gr or possibly .2gr if at all. There is really no difference in the two, buy them when you can these days! Treat them like any other change in components, rework the load like with any other component change.

 

[Demi-human]

Don’t pass the half way point between low and max charge.

Then what are the maximum charge weights for?

It would be strange for the primer to have more fuel in it than the powder. A magnum primer is not worth seven grains of BLC-2.

 

[Charlie98]

If you're pushing max loads I'd drop down some. If at or near start loads you probably won't ever notice.

That's my method. If I'm at max load, I don't change anything without reducing and working back up, but if I'm in the middle somewhere, and depending on the powder, it is unlikely there would be a problem. I will say, however, your load's performance might change... including velocity, and velocity spreads. I have done informal tests with both rifle and pistol powders, the only thing different is a standard or magnum primer... and there was always a difference.

 

[JFrank]

The way it was explained to me goes like this;
Your node will move slightly with a change of primer so with a bit of testing on both sides of your current charge say ..a couple tenths each side.. you should easily re acquire your accuracy node.
I found this to be true although your results may vary slightly I look forward to your reporting back

 

[The Remnant]

Thanks for the advice everyone. If I'm able to score some Magnum SR, I'll drop my powder charge a bit & work it back up & report back my results.

It's good to know that the Magnums are a viable option.

 

[Obturation]

I've heard warnings , never noticed any difference. I usually work up everything with mag primers and use them whenever possible, if I only have standard primers I don't worry about extra pressure. My max loads don't deviate from my test loads, things in the middle I can be a bit loose with my components if need be

 

[Walkalong]

I don't think I own any small pistol mag primers, I do have some large pistol mag primers left over from the start of my .44 Mag reloading when I used W-296 (In the metal one pounder), but moved on to AA # 9, and much later added N-110 to that.