Ruger has changed the complete profile of the firing pin used in the Ruger Mark I,II, III, IV & 22/45 pistols.
So far, I really like how well this new style of firing pin performs in the three Ruger Mark pistols I've tried a sample firing pin in. The firing pin tip has a smaller footprint that really seems to concentrate all the force from the hammer hit directly onto the rim of the cartridge in the most effective area to detonate the primer mix.
Here is a random sampling of the spent cases I picked out of the snow, from the three test pistols I was using.
I would consider these sample spent cases to have received excellent firing pin hits, and every cartridge went off perfectly. Now, I can't say why Ruger changed the design of these firing pins, but from my initial testing, I think they did a fine job.
Now, for sure, we can't position a cartridge in the chamber perfectly to the point where if the primer mix has not reached all the way around the inside rim of the case, that we will still get complete ignition. But still, I have some suspect .22 rimfire brands that are thought to have voids in the rim that didn't get any primer mix. Gonna test that ammunition with this firing pin, just to see.