Sako7STW ,,,,,
I have found that with all the Lazzeroni short mags like the Patriot, that the 210 primer gives a little more velocity at the same pressure, and much tighter shot-to-shot spreads on both pressure and velocity ,,,, as compared to the 215 primer ,,,, ((reloader 15 & 19 used for most of my testing))
"I" believe this is because, the higher percentage of powder that you have to the sides of the primer blast, instead of directly in front of it ((which is the case with short-fat cartridges, instead of long thin ones))) the more evenly the powder burns, and the more of it burns in the case, instead of going down the barrel, behind the bullet, contributing to projectile weight & recoil ,,,,
the 210 primer is not quite as hot and explosive as the 215, but seems to get the same job done in the Patriot without as much of a pressure spike, when it first fires ,,,,
kind of like switching to a slower powder ,,,, only without the negative aspects of a slower powder ,,,,
and it would make sense to me that this same idea would carry into other short mags besides the Lazzeronis, but I have no direct knowledge of that ,,,,