Otto,
Off center primer strikes in my brother's Martini 8.15x46R were caused by too thick rims(cases also made from 30-30 cases, with rim dia.reduced, but not thinned).Since the breechblock seemed to close, we didn't see a problem at first.We tracked the off center strikes to the thicker rims not allowing the block to rise completly.If you plan to try pistol primers anyway,I suggest you thin a couple rims from the rear( pistol primers are a little thinner anyway)and check both the firing pin firing a pistol primer, and striking it in the center.I am sure the offcenter strikes make it harder to fire the primers,especially since the original .254" primer wouldn't be as critical for this. If it was easy, it wouldn't be nearly as much fun and anybody could do it.
Mike
