Still trying to figure out the safety issue. As I've posted before, I prefer a thumb safety which is not available on the M&P Pro series. The 9mm Pro has a striker block safety. Can anyone explain what that is, and how it relates to the trigger safety, and a slide/thumb safety which is not avaialble? I am close to making a decision between the M&P and XDM (which BTW is on sale for $597, same price as the M&P Pro), and I'd like to understand the function of the SB safety. Does the M&P with a thumb safety also have a striker block safety? Thanks for any help.

All M&Ps have a striker block safety. The striker block safety has nothing to do with the trigger 'safety'. The striker block safety is in the slide. It simply prevents the striker from breaking the breechface until it is moved up and out of the way via the trigger bar. Basically, unless the trigger bar is pulled back (via the trigger) into the firing position, the striker is blocked from moving forward enough to discharge a round by the striker block.

It really helps to understand how whatever pistol you're choosing to purchase/carry works. The XD pistols, for example, also have a striker block safety. However, the XD pistols use two other safeties not found on the M&P: the sear shelf safety and the grip safety.

I used to not like the M&P because of its use of a simple spring sear instead of a more "Glock like" one piece trigger bar with attached 'sear' and the sear shelf. Over time, I've grown to like the M&P more and they are currently the only type of striker fired handguns I own.

My M&Ps all have thumb safeties, but the thing to remember about the M&P thumb safety is that all it's doing is preventing the trigger from being pulled back far enough to engage the sear. It does not prevent racking of the slide or movement of the sear in anyway. Therefore, the thumb safety is simply a personal preference item for the M&P pistol owner.

It really helps to know how your pistol functions. The M&P is a dead simple design. Watch some videos on youtube to get yourself a better understanding of the different firing methods used by various striker fired pistol makers (e.g. Glock, S&W, Springfield).

Thanks DandC, very helpful. So without the thumb safety, there is nothing other than your own wits to keep the trigger from inadvertantly being engaged.

Here's a good video from Glock's website showing how the striker block operates:

G17 Safe Action System - YouTube

The striker block is the small piece up in the slide near the front of the striker that moves vertically. Notice how when the trigger bar moves back, the raised portion on the trigger bar pushes the striker block up and out of the way thereby freeing the striker's forward movement.

The M&P striker block is located in a different place but it operates in much the same manner.

Just like a revolver. The M&P will not fire unless the trigger is pulled.
(That should give pause to the people who want a "zero take up" 2# trigger on an M&P)

All the add-on manual safety on the M&P does is block the trigger. The other safeties are what keeps the gun from firing if dropped, vibrated or jounced. I don't have the manual add-on safety on my M&Ps. If I catch you loading on my range with your finger in the trigger guard, for example, you're gone, external manual safety or not. Buy a gun with it if you want but it does not compensate for or excuse poor gun handling.

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