i am in the middle of fireforming 400 pc of brand new lapua 260 brass to 260AI. for some reason i've had 2 pierced primers in the past 50 rounds. i can't remember the last pierced primer I've had, but it has been thousands of rounds ago, and never while fireforming.
42g of reloader 17 has been my load for years in both 260rem and for fireforming 260 brass to 260AI. my 260AI load is a full 3 grains more powder and sometimes 4 grains more. so i'm somewhat skeptical that the primer piercing is due to overpressure. the primers ruptured in the center, but are not flattened. there is no ejector mark. the web of the case is exactly the same diameter as it was prior to firing.
both came from the same tray of wolf primers, but it is the last tray in the box of 1000 with none of the other 900 pierced.
i'm going to back my ff load off another grain just in case, but if anyone has any ideas what to check, let me know.
oh, coincidentally, AJ just sent me his bighorn firing pin disassembly tool which arrived a couple days ago. So i took the opportunity to disassemble it and inspect it. It has close to 12,000 firings on it, but looks none the worse for wear. The tip is not sharp or eroded.
42g of reloader 17 has been my load for years in both 260rem and for fireforming 260 brass to 260AI. my 260AI load is a full 3 grains more powder and sometimes 4 grains more. so i'm somewhat skeptical that the primer piercing is due to overpressure. the primers ruptured in the center, but are not flattened. there is no ejector mark. the web of the case is exactly the same diameter as it was prior to firing.
both came from the same tray of wolf primers, but it is the last tray in the box of 1000 with none of the other 900 pierced.
i'm going to back my ff load off another grain just in case, but if anyone has any ideas what to check, let me know.
oh, coincidentally, AJ just sent me his bighorn firing pin disassembly tool which arrived a couple days ago. So i took the opportunity to disassemble it and inspect it. It has close to 12,000 firings on it, but looks none the worse for wear. The tip is not sharp or eroded.