It'd be fanciful to think that Winchester would use somebody else's primers in their ammo. For just one thing, they say their primers are specifically tailored for use with Ball� powders.
Some labs - Speer was once one - used an in-house rule to use magnum primers with ALL spherical powders, no matter what. That ignored such things as case capacity, which is a major consideration for primer choice. Lately, that inflexible rule seems to have been set aside, thank goodness. Current data books that I've seen now show a mix of standard versus magnum primers even with spherical powders. The choice may revolve around case capacity and the particular powder used - which are the two proper decision points, IMO.
Years ago I followed a Speer recipe for 22-250 and used a magnum primer with a starting load with a ball powder and blew the extractor off of my Custom Sako.Case volume has everything to do with the use on a Magnum primer!!!!!
a 22-250 would be a mag in my books.. bore diameter vs case capacity....
The mag primer didn't blow the extractor, it was the bad load data that did more than likely.
I run all mags in 223 cases well over 100K rounds fired in the competition years.... probably well more than that actually since it was up to 20K a year at times. And I ran probably 50/50 ball and extruded powder.
My rule.... try to take the best info you can IE what powder/primer combo is suggested most as a match... IE in 223 Varget and CCI BR4 and you need look no further..... and then I test.
I never write off a primer as I've ended up using every last one at some point or another in combos through a barrels life while playing with different stuff.
primers are one thing that I've noticed can cut a group in half or double or triple it by simply trying another primer with a certain powder in a safe load..
