Kimber has begun to install what they call the “Series II” firing pin block. (It is essentially a resurrection of the Swartz safety developed for Colt before the Second World War). When you depress the grip safety, a small pin pushes a plunger up in the slide which unblocks the firing pin. I do like it better in one respect than the Series 80 firing pin block of Colt: it is activated by the grip safety, not by the trigger (see diagram), so you get the clean trigger pull sans the click and crunch of the Series 80 guns. You have to be careful when you field strip and reassemble a Series II Kimber because if you hold it by the grip and activate the grip safety, a little pin comes up next to the disconnector and it will stop the slide from coming off or going on, and if you get muscle-bound with it, you could shear the pin and render the gun unable to fire. Also, the FPB mechanism can only be accessed by removing the rear sight should you need to do cleaning or maintenance on it. I’m not terribly wild about this characteristic. (I still believe this is a lawyer-friendly answer in search of a question. I continue to search for documented instances of 1911 pistols going off from being dropped on their muzzles, and I have yet to find one documented instance of an unmodified 1911 in good repair discharging due to a drop on the muzzle from any kind of normal height – if you find one, please send it to me).