Primers What's the real difference?

[truck driver]

I have always been told that magnum cartridges require magnum primers or heavy loads of slow burning powder.
On the label of a can of H4350 there are suggested loads and what primers to use. The 300Wm load uses LR primers where the 338Wm load with less powder uses a LRM primer.
My thought was anything loaded with slow burning powder H4831 and slower required magnum primers.
Are magnum primers required or is it just a powder/ bullet manufactures suggestion/

 

[domdoc]

There is no answer which addresses all situations, with regard to primers. Match primers are typically the same as standard, except they are put together by the most experienced employees of the primer company. That's what I heard with regard to CCI. Some primers have a thicker shell, which may make them less likely to ignite when hit by a firing pin drifting forward when the bolt closes on an M-1 or M1A, or AR-15. As for magnum cartridges, I have definitely seen .300 Win Mag shoot horrible groups with a magnum primer and IMR 4350; then a knowledgeable friend told me you only use magnum primers if standard primers won't produce good groups, specifically with IMR 4350 in a .300 Win Mag. He was right. I have also heard that magnum primers are more likely to produce good results with powder that is harder to ignite, such as ball powder. Those are things I've heard and seen. Anything other than that, test it yourself. When the powder company literature says to use a magnum primer, they most likely have a reason, but they don't say why. When changing any component, it's a good idea to back off the load, and work back up.

 

[darkhorse95]

Honestly just load them both and test it. Like domdoc said ball powders tend to like mag primers. H414 and 123 eld-m got me 1in groups with cci standard primer, .4moa with mag primers.

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[usafa77]

CCI has a pretty good explanation on their website.