Effect of Magnum Large Rifle Primers on .308, .30-30 & .30-06 Loads

In this time of primer scarcity, I decided to get all my primers in one location and make an Xcel spreadsheet to track usage. Well, after reading about the shortage of LR primers on here the other day, I found to my surprise that I have 5,500 LR magnum primers. My only use will be in .308, .30-06, .30-30 and .45-70. I think the reason I bought them years ago was that I was shooting a lot of .45-70 loaded with Pyrodex, I know, boo-hiss, but it was and still is the only game in this area.

My question is, how much, if any will I have to modify my smokeless loads using the LR-M primers? Thanks in advance for all input. GF

I use LR mag primers with ball powders like W748 in 308 and H414 in 30-06. my loads are slightly under max. Have had good results accuracy and performance on deer.

You might want to try a few with a slightly reduced load, but you should be OK.
I use a lot of Winchester LR primers in those same calibers, and they say they're for both standard and Magnum loadings.
I load to about 85-90% of max. published data with 3-4 different IMRs and Win 748. Never had an issue.

I use a lot of IMR4895 & 2400. I don’t use “hot” loads. Cast, jacketed, and M160 frangible bullets. I’ve seen no difference. I use the same amount of powder.

I forgot I did see one difference: a Shilo Sharps wouldn’t reliably pop magnum primers.

Thanks for all the input. It is nice to know during this time of high prices and scarcity. GF

unless your already running a really hot road...you wont notice any difference.
Ive used them in 7.62x39mm 308 270 30-06 22-250 and 45/70 forever...only use std primers occasionally..just because 30 years ago the magnum primers were recomended with 2213sc....

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Originally Posted by Gray Fox

In this time of primer scarcity, I decided to get all my primers in one location and make an Xcel spreadsheet to track usage. Well, after reading about the shortage of LR primers on here the other day, I found to my surprise that I have 5,500 LR magnum primers. My only use will be in .308, .30-06, .30-30 and .45-70. I think the reason I bought them years ago was that I was shooting a lot of .45-70 loaded with Pyrodex, I know, boo-hiss, but it was and still is the only game in this area.

My question is, how much, if any will I have to modify my smokeless loads using the LR-M primers? Thanks in advance for all input. GF

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NOTE this is 2nd-hand info, from my (now deceased) buddy, Ed. Not any different from most all of us, Ed could not pass on a bargain -- and he heard of an avid shooter moving to a "warm state in the States" -- one of the Carolina's? -- for retirement, and had all his powder and primers up for sale. Ed bought the entire kit and caboodle! "Where did I get 'involved'?" I had two Chronies -- Ed didn't have any -- so he borrowed my PACT to ascertain differences -- if any -- using magnum vs. bench-rest (fellow had a lot of these) vs standard primers. For what it's worth, Ed passed on to me that the magnums MAY be "hotter" -- but from the chronograph, the velocity differences were marginal. Added also is while was in many ways frugal, vis the firearms in his collection, ALL were "top shelf"! He (child-less) cared for his firearms as a new father might for the baby -- and ended up using/shooting ALL he purchased except for one jug of powder he never could find data on.
geo

I posted this on another thread earlier this year. It's only one cartridge using a surplus powder no longer available but I think it gives you a pretty good idea of what to expect if you are not at maximum loadings.

"About 10 or more years ago I inadvertently bought a thousand Winchester large rifle magnum primers. I don't load anything that required them, and they they sat unused until the primer shortage became a reality for me. Wanting to compare the two, I loaded both types in some Remington 30-30 cases with the Lee 150 grain FP and some surplus CMR100 powder with the following charge.

PRIMER POWDER CHG. VEL
WLR MAG CMR100 28.3 2030 ES 67fps SD 22fps
WLR CMR100 28.3 2040 ES 66fps SD 23fps

These were fired in my Savage 340 with an 18 inch barrel and as you can see, there isn't much difference. Both loads shot very nice groups and I was surprised that the standard primers actually gave a bit more velocity. I don't know if CCI magnum primers would give the same results, but I'll bet they aren't going to be much different."

From everything I read, they only jump an average in velocity of 50 fps….if that. I used magnum pistol primers in my trail boss 45 colt cast loads by accident. They are under 400 fps with a 5.2 grain load. Just ladder test with your load and check for pressure signs along the way. My guess you won’t notice any difference in pressure signs from a standard to a magnum primer until you get way up on, or above, max book loads.

I tested every flavor of primer I could get, did everything I could, to get every brand; and test in my 45/70. I only changed the primers. I shot everything over a coronagraph. Only mild loads. The only difference I came up with was; Federal/CCI magnum primers shot at about 100 FPS more than the rest of the primer brands, which were very close to the same FPS across the board, in my guns; I use only magnum primers for reliable ignition in cold weather; IMHO... . Match primers were supposed to be more consistent ?? I was told that when they ran out of match primers they would just fill the boxes with regular primers ??? YOU must run your own tests and see what is in your guns ??

I did some pretty extensive, although only chronograph based, testing early during COVID. In all cases it was putting magnum primers into non-magnum applications such as SPM into 9mm loads. I detected no velocity variation outside of the norm for my loads and no signs of pressure loading in the top 75% powder ranges. This certainly isn't gospel, but with the age-old advice of start low and work your way up, you should be fine.

I still have two bricks of magnum LR, and I wouldn't hesitate to use them for any of my cast loads except one: 30-30 loaded with Lyman #311041 and 34.0 grains of Levereloution. That powder works great with standard primers, but even though they're probably perfectly safe, that powder is just too much of a grey area for me to experiment with. I'll stick with know loads on that one. For everything else, I've used magnum primers in everything from 7.62x39 to 30-06 with no issues.

I used a few cci 250's today to try on my 35 whelen loads. The load data I used that had the cci 250 magnum primer was listed in Speer's along with 2460 powder and 180 grain hot core. I substituted 2230-c powder for 2460. Can't wait to see how it groups with my ladder testing and the powder. If I get a nice tight group I'll re test with some cci 200's and see if my group size changes. Rather keep my Brick of magnums for the RUMs.

By "hotter" if you mean higher pressures, you are more than likely incorrect. The use of magnum primers in the cartridges mentioned by the OP can generate higher pressures, especially in colder temperatures, because they give better, more consistent ignition with slower burning powders, especially ball powders.

Magnum primers are not simply filled with more of the primer mixture. The magnum primer mixture is a different composition designed to give longer and, sometimes hotter, flame than is used in standard primers. Given the volume of the mentioned cartridges the additional amount of pressure that additional flame may produce isn't very much. What happens that may show an increase in pressure is the pressure may increase earlier in the "rise to pressure" because of the better ignition, especially of the slower burning powders in large volume.

With the faster, more easily ignited powders most often used with cast bullet loads little or no difference in velocities will be observed. However, different meaningful pressure differences can sometimes be measured in smaller capacity cases.

For cast bullets, at medium or faster velocities (not mouse fart loads), LR magnum primers may shrink your groups. I always work up load with standard velocity primers then try that same load with magnum primers. Sometimes, it will shrink groups. Also found that magnum primers eliminated fliers when testing a proven load, developed in warm weather that balked at sub freezing (hunting) temperatures. This was in large lacapity cases (338W) with moderate loadings of SR-4759, 4189 and 4895 extruded rifle powders. Try it, you may like it.

Winelover

Large rifle magnum have been the most difficult to find. At least in my area. I'll bet you could find a friend or club member to trade with.

GONRA's younger son is an EXTREMELY careful handloader....
BUT - his record keeping is "casual".
(He's generating data for 300 Rum with WW II AP bullets.)
Stay Tuned.......

I was also under the impression that magnum primers also consisted of a slightly thicker material.

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Originally Posted by Latheman

I was also under the impression that magnum primers also consisted of a slightly thicker material.

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They used to. Most all US made primers use the same material of the same thickness for all primers. Cheaper production costs.

There’s a really nice article in the Hodgdon reloading data magazine that Santa Claus put in my stocking this year. It talks exactly about this using magnum and regular primers with a bunch of loads. They tried it in velocity gains and pressures. It’s a good read if anybody has a Walgreens there about 15 bucks for the magazine with all the load data or I should say not a lot of load data they don’t have any 35 Whelen in it. My guess is they just put load data in for a lot of the new cartridges that’s for some goofy reason. Kind of weird.