I posted about this a while back on another thread, but it didn't get much traction. People may not have grasped the importance of a strong firing pin strike in the right location that produces better, more consistent powder burning.
Most rifles firing pins are not shaped properly to hit just below the fold of the rim, where the priming mixture is and where the metal is easier to dent. The ideal firing pin nose is best shaped to avoid hitting the fold and shaped to provide a sufficiently narrow, yet rounded have edges, with the most forward portion at the bottom, where it can create a fanned flame that provides the best priming mixture and powder ignition.
A great rimfire rifle gunsmith, Calfee discovered this firing pin improvement method and it really works great. IMHO, it's especially important for .17 HMR and .22 Mag shooters interested in long distance accuracy from their pet rifles.
Before (left) and After firing pin shape mods.
Having such a firing pin shape and impact location also tends to minimize semi-auto vertical bolt movement effects on the shot, whether by sloppy bolt travel or varied upward pressure by vertical-stacked cartridges in a box magazine. Note that some shooters don't fully load their magazines because they've noted first-shot variation in groups. (Also note that rotary magazines may provide more consistent upward force on bolts.)
Most rifles firing pins are not shaped properly to hit just below the fold of the rim, where the priming mixture is and where the metal is easier to dent. The ideal firing pin nose is best shaped to avoid hitting the fold and shaped to provide a sufficiently narrow, yet rounded have edges, with the most forward portion at the bottom, where it can create a fanned flame that provides the best priming mixture and powder ignition.
A great rimfire rifle gunsmith, Calfee discovered this firing pin improvement method and it really works great. IMHO, it's especially important for .17 HMR and .22 Mag shooters interested in long distance accuracy from their pet rifles.
Before (left) and After firing pin shape mods.
Having such a firing pin shape and impact location also tends to minimize semi-auto vertical bolt movement effects on the shot, whether by sloppy bolt travel or varied upward pressure by vertical-stacked cartridges in a box magazine. Note that some shooters don't fully load their magazines because they've noted first-shot variation in groups. (Also note that rotary magazines may provide more consistent upward force on bolts.)