S&W Equalizer/M&P EZ Safety Mechanics

TLDR: Read the bold section.I recently picked up a Smith & Wesson Equalizer to try out, which uses (as far as I can tell) the same fire control as the EZ line. Before purchasing, I couldn't find a lot of good detail on how the grip safety and optional thumb safety interacted with the rest of the firing mechanism, but it's something I was very curious about. Now that I know from spending time with my Equalizer, I thought I'd post the information in a consolidated place, and share a minor concern I have with it. I'll start with a detailed description of the internal safeties, followed by my main point (in bold, for TLDR).(I realize that pictures/video might be better for this, and maybe I can post some later, but this will have to do for now, and is easier to find via keyword searches for curious people in the future.)The Equalizer uses an internal, single action hammer firing mechanism. There is no half-cock notch, but if the hammer falls due to malfunction, a plunger-type firing pin block will arrest the firing pin and prevent it from striking the primer of a chambered cartridge (most of the time - more on this later).This firing pin is the same length as the firing pin channel, meaning it will not protrude forward of the breech face when the hammer is fully forward. Instead, it relies on inertia to bounce or leap forward of the breech face when struck by the hammer, and then retracts under spring tension. This helps to prevent slam fires, and means the firing pin is always returned to a neutral position after each shot, where it can be arrested by the firing pin block.The grip safety performs two functions when depressed. First, it lifts up the trigger bar so that it can engage the sear when the trigger is pressed. The trigger can still be pulled fully to the rear when the grip safety is not depressed, but the trigger bar will not be able to interact with the sear. Second (but simultaneously), it raises an arm which pushes the firing pin block out of the way, so the firing pin can move freely. This second function of the grip safety can be surprising to someone used to the more common approach of having the trigger pull disable the firing pin block, but it is similar to Swartz safeties found in some 1911 pistols (and possibly other systems), and makes for a better trigger pull.The optional thumb safety likewise does not prevent trigger movement, but like the grip safety also prevents the trigger bar from rising into contact with the sear. When a thumb safety is installed, it must be disengaged AND the grip safety must be depressed in order for the trigger bar to come into contact with the sear. The thumb safety performs no other functions as far as I can tell.Now for the concern. Neither the grip safety nor the thumb safety block either the sear or the hammer. With the slide removed, the thumb safety engaged, and the grip safety released, it is still possible to drop the hammer by poking the sear with a finger or pencil tip. In the event of a mechanical failure with the sear interface (which has happened in at least two instances; see the M&P EZ recall from a few years ago), the hammer WILL fall regardless of the condition of the safeties.Really, this is no different than on many striker fired pistols like the M&P line which are held at full cock, and where nothing prevents the striker from moving forward with full force if the sear fails. In such cases, we rely on the striker/firing pin block to prevent the weapon from firing. On most pistols, though, the trigger disengages the firing pin block, so as long as the pistol is in a quality holster that prevents diddling of the trigger, the firing pin or striker is guaranteed to be held in place by the block.However, on the Equalizer, the firing pin block is disengaged by the grip safety. No matter how good of a holster is used, the grip safety (and thus the firing pin block) is always vulnerable to being actuated by anything that comes in contact with it, like some bunched up clothing, a roll of fat, a backpack, or what have you. If this coincided with a mechanical failure of the sear interface (which has happened with the EZ line), it would certainly result in the gun discharging without the trigger being pulled.I'm not at all saying that the Equalizer or EZ line are unsafe, and there are understandable engineering trade offs with any system like this. The failure mode I described is incredibly improbable. It's far more likely that your friends will tease you to death for owning a pistol called the EqUAliZER. However, it is worth being aware of.Hopefully this post will be of interest to anyone who's also curious about this, because I looked and looked and couldn't find a good description of the internal safeties before purchasing mine.TLDR: Read the bold section. via /r/CCW https://ift.tt/rL5wXhM