Originally Posted by Rastoff

First of all, realize that this thread is a year old and you may not get responses from some of the previous participants.

If you use the proper grip, this is impossible. Your shooting hand thumb should be on top of the thumb safety.

Wrong.Wrong again. Well, the engineers do indeed know what they're doing, but the striker in an M&P is fully cocked.

I don't know where the 98% number came from, but it's wrong. If the striker moves at all from pressing the trigger, it's only because two flat surfaces that are touching will cam one surface as the other rotates. In the case of the M&P, the sear is only rotating about 5° which means the 1/64" of sear engagement will move the striker about .001" as the sear rotates. This does NOT cock the striker more or add any significant power to the striker.

If somehow the sear were to fall out of the way and the striker block was defeated, the gun would fire without the mythological extra move.

You are correct to say that the thumb safety is not really needed. All it does is block trigger movement. Some like it because it does reduce the possibility of ND while re-holstering.