Large Rifle primers in a magnum

[Thursty]

So, I need to do some loading for my 300 Win Mag. I currently have large rifle primers on hand, but no magnum primers. Times being what they are, I’m thinking I’ll need to try the standard primers instead of the magnums. I’ve never loaded for a magnum before, so never had a need for magnum primers. Anyone have experience running standard primers in place of magnums?

[Quavodus]

I've never loaded for a Magnum cartridge but, lots of .308, 8mm Mauser, and .30-06. I use to load a lot of IMR4350 in .30-06. And it's kind of on the slow side. I always used standard, mostly CCI200. Never had a problem. Just give it a try and see.

[scatman]

Hey, so mag vs standard primer difference is simply this: magnum primers have more oomph and ignite slightly faster. As far as loading with a standard primer where a load calls for a magnum, you will notice about 200 fps decrease, if not more, in muzzle velocity. If you're using a load book like Hornandy's 11th edition, you will notice that with a standard primer you get the minimum load's muzzle velocity with the next step up from that load. This has been my experience over the last few years in the struggle to find certain primer types. I am currently loading my 9mm with magnum primers because that's all that is available to me at the moment. I'm having to use less powder because the magnum primer puts more pressure behind the round.

[JustEd]

For reloaders, this is the new bright age of..."try it and see what happens"

Don't use "magnum" primers in any of my reloads, but have swapped rifle for pistol primers.  SP vs SR primers make no measurable difference in velocity, 9mm and 38 spl.  To my understanding the base material is thicker and that is about all.  On magnum primers, I do not know if it is simply a matter of thicker base or if they are indeed hotter.  Work up some loads with the standard primers and look for primer deformation to tell you when it is getting too hot.

[scatman]

On 6/29/2022 at 8:49 AM, JustEd said:

For reloaders, this is the new bright age of..."try it and see what happens"

Don't use "magnum" primers in any of my reloads, but have swapped rifle for pistol primers.  SP vs SR primers make no measurable difference in velocity, 9mm and 38 spl.  To my understanding the base material is thicker and that is about all.  On magnum primers, I do not know if it is simply a matter of thicker base or if they are indeed hotter.  Work up some loads with the standard primers and look for primer deformation to tell you when it is getting too hot.

Magnum primers are indeed "hotter," and thus give slightly higher amounts of pressure. If you note my previous comment, I go more in depth about the differences, and my first hand experiences.