I was just on the Hogdon's website and they listed small rifle magnum primers for the 300BO and H110? I don't load for that cartridge but wondered why they did? Just a curiosity to me.

I use what gives me the best accuracy and could care less what the "label" calls it. i've used a lot of R7.5 which are supposed to be mag strength... lots of M41s and 450s. And lots of BR4s with the 223. And before the WWSR were brass, when they were silver nickel plated I used a lot of them too... FWIW.

IIRC H110 takes a fair fire to light it good, again IIRC.

Originally ALL small-rifle primers had thin cups, because all the cartridges that took them were relatively low-pressure, none developing pressures over 50,000 PSI. It wasn't until the 1960's, when the .223/5.56 appeared, that the first so-called "magnum" SR primers appeared, and then they were primarily heavier-cupped, not "hotter."

Over the last half-century more thicker-cupped SR appeared, mostly because of more factory cartridges based on the .223 case that operate at over 50,000 PSI. Some are hotter-burning and some are not.

The .300 BO's standard SAAMI maximum average pressure is 55,000 PSI, which aside from powder selection is probably why Hodgdon used a magnum primer.

The primers Jeff lists are all thicker-cupped.

over the years I have noticed when all of the ar15 guns fire and you eject the next cartridge by hand without firing it, there is a little dent in the center of the cartridge primer from the floating firing pin. Over time I have moved away from federal primers as people always claim they are soft and will slam fire in an ar, not seen it but others here won't use them. So CCI is all I use now in those guns, and its good to know that you can substitute a small rifle magnum primer for a small rifle primer, that knowledge might come in handy someday.

their new CFE BLK looks interesting as well, I see they have a 6.8spc load for it.

fed will slam fire in an AR. I"ve seen it a few times, had it happen to Carolyn once.

So will the new WWSR primers, I saw that a few times while shooting years ago...

Not very dang often though.....

Yep, Johnny Buffalo is spot-on, as usual. Absolutely totally correct.

Most handloaaders assume that magnum small rifle primers are hotter than standard small rifle primers. And that simply is not true. The only difference is the heavier cup ... so that they can withstand higher pressures.

Blessings,

Steve

Well, some of them are hotter. My point was that while "magnum" SR primers aren't always hotter, they're always thicker-cupped--and the primary reason is pressure.

Then again, some "non-magnum" SR primers have thicker cups. It gets confusing!

Johnny Buffalo...I like that

Yep, my Forever Friend John and Roomie, John, got into the habit of calling me Stevie Prairie Dog, or some such sh1t

Anyway, he and I killed Asian water buffalo during the same year. I guess we are "Brothers of the Bull."

Big sonsofbitches, for sure.

Blessings,

Steve

"Big sonsofbitches, for sure"....Are you referring to the prairie dogs and the water buffalo or you and Johnny B?:-)