A friend just bought some CCI small rifle magnum primers and gave them to me. He didn't realize they were the magnum variety and bought them by mistake. What purpose do they serve? What small rifle cartridge really needs a magum primer? Maybe I can reduce the powder charge slightly in .223 just to get rid of them?

On the other hand, I have some annoying Federal .45 ACP brass with the small primer pockets that are very deep, so deep that Federal's own small pistol primers misfire when seated to the bottom of the pocket. Maybe these primers would work with this brass and a slow powder like 2400 when used in a carbine?

Dave Sinko

I use SR Magnum primers in my 223 when loading ball powder like W748. I believe you would also consider Remington 7 1/2 primers as Magnum.

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Dick

Remington 7 1/2 primers were designed to handle the higher pressures of the 17 Remington cartridge by having a slightly thicker cup. I think I read somewhere that all small rifle magnum primers have a slightly thicker cup. FWIW

I have used small rifle magnum primers for 223 and have not seen any discernible difference from using standard primers.

The cup is supposed to be thicker in the magnum primers, allowing them to withstand pressure better but also requiring a harder strike to ignite.

From postings I have read in the past it seems like there is not a lot of practical differences between magnum and standard primers when used, be it pistol or rifle.

If you are wary of using the magnum primers, send them to me and I will make sure they are safely disposed of, one at a time

I use small rifle magnum primers when loading 454 Casull.

5.56, I believe. Not sure of the NEED of them in any other caliber though. My knowledge is limited loading for rifles that use a small primer though!

My .454 Casual recipe calls for small rifle match primers and I use Remington 7 1/2. I am sure the CCI small rifle magnum would work fine.

Magnum powders are typically used with slower burning ball powders. Some of them have a coating on them to slow the burning rate, and the hotter primer is necessary to properly ignite the powder in the first place. Your powders are safe to use, but you really need to do your load development over again since you changed a component.

The SRP is recommended in AR's due to the thicker cup. The floating firing pins will slap the primer when you drop the bolt to load the gun... check that out and you will see a small indent on the primer.

That is what I use mine for--A warmer load of 2400 with mag primers. Good for over 100 yards in my Marlin 357.

I'm using magnums for my .223 load with w748 powder

It's been a great load.. I actually just purchased my first brick of non magnums, because I'm going to start a new load with imr so I can use the same powder in 223 and 308 loads

I used my chronograph to check 223 loads with different powders and both standard and magnum primers. The primers didn't seem to matter - except for surplus 844 powder. With 844, the standard primers gave a very large "extreme spread", but with magnums (Rem 7 1/2) I got excellent results and groups.

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6/23/2022

Magnum primers are used a lot with Hornady powders that are the ball type and also the slower powders for better ignition and can also give better fps readings as well as accuracy.
They can some times add a few fps to a load as well as higher pressures, so care is needed if switching from a standard primer,if reloading.
I will also use magnum primers when the temperatures drop below 40 degreesfor my hunting loads. One year in 10 degree weathwer I had two misfires with cci standard primers, that cost me a larg buck.
I mostly use the mag primers for the higher velosity loads where they generally work best and save the standard primers for target and middle of the road loads.

Please don't use those small magnum rifle primers in you 45ACP blazer brass.

Please do use them with your .223 loads. Just drop a half grain and work back up.

Some older manuals called for them anytime ball type powders were used. I don't see it as often in the more modern manuals I have.

Also as above, using them with an appropriately adjusted dose of powder in place of milspec primers in anything with floating firing pin is considered an acceptable, safe practice. They're a bit tougher both in construction and sensitivity too slam fires.

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GOA
USA Shooting Supporter

My Lyman #47 recomends them for .223 with H335.

No offence intended, but if you gotta ask, no they won't be of any use to you. Loads are made up of a variety of components; bullet, powder, primer. Some powders work better with magnum primers and with some, they don't make much difference. Reloading manuals are ment to be suggestive only; they list what pressures are arrived at with a certain combination of components in the test equipment the test techs used. On occation, a simple substitute of primers can improve accuracy signficantly. Experienced reloaders take this into consideration when working up accurate loads...

A SRP has only a little more energy than a SRMP. Actually a SPM has a lot more than either. Some food for thought

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Still Running Against the Wind

Don't use magnum primers with 2400. It is neither necessary nor recommended. Save them for when using a ball powder.

Don

I use small rifle mag primers behind H335 in my 100 yard load. I worked the load up back during the Clinton primer scare when they were all I could get.

That is a very good use for those CCI450 primers, in semi-auto 223 ammo.

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Freedom is never free!!
SWCA #3437

I seated a few of these CCI 450 Small Rifle Magnum primers in the CCI .45 ACP cases and they are a perfect fit, seating just below flush. I am considering loading a few of these with a moderate charge of 2400 and some kind of cast bullet. I'd like to try them in my 625s and Glock 21s (with Bar-Sto barrel). I don't think there is any great risk involved here, other than light hits and misfires.

Dave Sinko

I don't think 2400 is recommended for use in 45 ACP, too slow burning. Can you find any load data, in a manual, for that combination?

I have seen loads that go up to 14.0 grs. with a 255 gr. cast bullet. I'll reduce a few grains of powder and see what happens. I'm mostly interested in determining if my 625s and Glocks will fire the thicker rifle primer. I'll probably try a 225 gr. bullet and Power Pistol in the Glocks.

Dave Sinko

Why would anyone do this?

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GOA
USA Shooting Supporter