Home Forums Hunting & Shooting Ask The Gunwriters magnum primers

I have pretty much switched to them for all of my rifles.The .243 and upwards.It seems to me better ignition is always a good thing regardless of the powder or powder charge .I have read that using the hotter/magnum primer is like adding a grain of powder sometimes, but with the powders I use it seems less to me.I would like some feedback on this-thanks

A good place to start is by getting a copy of the 2015 Hodgdon Annual. Brian Pearce, a meticulous and knowledgable fellow, wrote a piece on the effect of using different primers with various rifle and handgun loads, including SD and pressure data. The results are surprising.

Personally, since I don't hunt in sub-zero conditions and use standard cartridges, I have no use for magnum rifle primers, and only use magnum pistol primers with LiLGun .357 loads. I may end up with small rifle magnums in .22 Hornet LiLGun loads, but currently I'm using H110 with excellent results (if somewhat higher pressure), and standard sp primers like CCI 500 and Fed GM100M work perfectly there.

Some sources call for LRMs for spherical powder rifle loads, even with standard cartridges, but I had a small pressure adventure with a .257 some years ago while still a couple grains off of max, and that cured me of going off the reservation without good reason (and data).

Magnum primers don't always help, and in fact can hurt the performance of some easily-ignited powders. It depends on the specific cartridge, bullet and powder.

But because of the same factors, they can also help in specific instance where they're not usually suggested. I ran a test on primers in the .22 Hornet a couple years ago, where many people (and even one major manual) recommend small pistol primers across the board. In the specific load I tested, 13.0 grains of Li'l Gun, CCI 450 small-rifle magnums produced the best results in both velocity and accuracy. But Li'l Gun is a relatively slow powder in the Hornet, and because it's a spherical powder, relatively difficult to ignite. Small pistol powders worked better with other combinations.

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Well I'm Western Canadian so we do hunt in very cold temperatures.I had read somewhere that powder charges over 60 grains would be when when you would switch to them.The powders I generally use burn fairly slow,4350 being about the fastest.

I have a 7x57 that likes 140gr bullets and a stiff charge of H414, but only if I use magnum primers. It's the only non magnum that I current load for where magnum primers give me the best results. Firearms and women are alike in that when you find out what they like best you'd best not fight it, just make sure they get lots of it. You'll be happier in the end.

With that in mind, you might want to read the articles in the 2015 and 2016 Hodgdon books on the new Enduron powders that are temperature insensitive. The authors tested the new powders at hot and cold temps. JB had a hand in some of this.

You probably know this, but just in case, be sure to work up from the start with the mags, don't just swap 'em out after you develop your loads. There's no "rule" of formula for exactly how much difference they'll make. Every load will likely react differently.

I consistently get 70 fps more with WLRM as compared to CCI 200 primers with Big Game powder and 120 NBT from my 7mm-08.




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Correct me if I'm wrong but I fired both the cci large rifle and the federal magnum primers in a rifle of mine just to see muzzle flash and noise comparisons at dusk and they seemed pretty much the same .I expected more of both.The magnum primers must only be marginally hotter.Oh yeah, my hearing is crummy. Thanks for any feedback on this

I'm under the impression that magnum primers burn a bit longer than large rifle primers. I did get my best 5 shot groups with Fed 215 primers in a 25-06, but was unable to improve accuracy in a .270 with them.

Flame duration or volume of gas produced may be different, but other characteristics are in play. The temperature of the burn could be higher, as well as the brisance.

Maybe a guy should measure the temperature at the muzzle...just for curiosity sake..How are primers measured anyways?Muzzle flash appeared about the same to me.

Muzzle flash doesn't have much to do with primers--or, as many people think, still-burning powder leaving the muzzle. Instead, all the powder kernels that are going to burn did so in the first few inches in front of the chamber.

What's left going down the bore behind the bullet is hot gas, which re-ignites when it hits the oxygen of the atmosphere. What you're seeing isn't burning powder, but burning gas.

A "hotter" primer primarily performs two jobs. First (and probably most important) it does a better job of cutting through the burn-deterrent coatings on spherical powders. Coatings are what control the burn-rate of sphericals, since the granules are all pretty much the same tiny size, whether the powder is fast- or slow-burning. Because of the coatings, spherical powders have a reputation of being hard to ignite, especially in cold weather. As noted in my first post, magnum primers can help ignite even small charges of sphericals more consistently.

Magnum primers can also be useful in igniting large amounts of extruded powders, which because they don't depend as much on coatings to regulate burn rate, normally ignite easier than spherical powders. But yes, 60 grains is a good rule-of-thumb for choosing a magnum primer even when using extruded powders. My .338 Winchester Magnum shoots very well with a charge 66-67 grains of Reloder 15 and 200-grain bullets, but only with a magnum primer. Standard primers result in groups at least twice the diameter.

But at the other extreme, relatively small cases loaded with extruded powders (especially short cases) often produce finer accuracy with standard-strength primers. The Federal 205M preferred by most benchrest shooters in the 6mm PPC is a good example, since it's just about exclusively paired with small-granuled, easy-to-ignite extruded powders. But it's the worst primer I've tried in the .22 Hornet with Li'l Gun, a quick-burning spherical.

Magnum primers can either contain more of the same sort of compound used in standard primers, or a hotter-burning compound. Some have used both over the years. Contrary to popular belief, the Federal 215 is NOT the "hottest" (whatever that means) large rifle magnum primer. The compound in the CCI was changed around 1990 to a hotter mix, and even Federal makes a hotter primer called the 216, developed for really big cases like the .416 Rigby and .470 Nitro Express--but doesn't sell the 216 to handloaders.