Angus,
That was something else I was going to bring up concerning Bob's post. When I have visited the Federal primer-making facility, they've emphasized that Federal Match primers are exactly the same as the equivalent non-match primers in every way--except consistency. The F215M's are not hotter than F215's. (Have also visited the CCI primer factory, and they say the same thing about their standard and "benchrest" primers.)
Also, though 215's were the hottest American primer made when they appeared, CCI switched to a hotter priming compound for their magnum primers in the early 1990's, and claimed they were then hotter than 215's. But one thing I've noticed is that most primer manufacturers don't announce changes in their already-produced primers, I would guess because they want handloaders to feel confident they're getting the same product.
I know there have been three different versions of the CCI 450, their small-rifle magnum primer, since it was introduced in the 1960's. The first used the same amount and type of priming compound used in CCI 400's, but had a thicker cup to withstand the higher pressure of cartridges being introduced then, primarily the .223 Remington. The next version used more of the same priming compound, to better ignite some powders, especially sphericals. The version now made was changed, like 250's, in the early 1990's to a hotter priming compound.
I also switched from F215's (both standard and match) to CCI's a few years ago, because Federal primers became so scarce during the Obama panic. If anything, many of my loads improved in accuracy when I switched from F215's (both versions) to CCI 250's, and most loads also gained a little velocity, indicating the 250's are indeed a little hotter than 215's. But as noted, often primer manufacturers make changes without making a public announcement. (Will also note that Federal also makes an even hotter magnum primer, the 216, for extra-large cases such as the .470 Nitro Express. But they don't sell them to handloaders. I have some, given to me by a piezo lab during one of my visits years ago.)
Will also note that even pressure-lab techs will disagree on primer performance. I known two guys in charge of BIG labs for decades, one for a powder company and one for a bullet/ammo company. They have different preferences in rifle primers, one preferring Winchester and CCI, the other Federal.
There are also quite a few shooters who prefer rifle primers made in Europe, claiming they're more consistent. In fact I switched 2-3 years ago from American small-rifle primers in my 6mm PPC benchrest rifle, because Sellier & Bellot primers provided a small but noticeable edge in accuracy.
