Well after many weeks of waiting I finally got some berger 168gr hunting VLDs for my dads 7mm magnum. I loaded up 3 of each charged cartridges ranging from 69-72 grains of H-1000 with Fed 215 magnum primers with overall length just long enough to fit the Mag. box. I went out today and cleaned the rifle from top to bottom. Then I fired the first group with 69 grains all was fine and dandy great group for the rifle .80s, then I shot the 69.5 and rite off the bat I new I had pressure, I ejected the first shell and primer was flat as a pancake and starting to run over the primer pocket, this went for the next 2 shots as well. The group opened up to well over 1.5". I have never had such a pressure jump between the first and second load grouping and usually run full charge and never show pressure signs. My question is why such a jump in pressure with low charges. I Know everybody says magnum primers count as 1gr of powder themselves, if this is true that might make sense then Id only be 2grains under max. Anybody got a clue? All the powder was out of a brand new 8lb jug I just got from Powder valley 2 weeks ago so no different lot numbers and all the primers came out of the same tray.