Slide movement in dry fire

[Lior]

Hi everyone. In my experience, one of the idiosyncrasies of M&P pistols is that when one dry fires them, the slide moves forward about a thousandth of an inch. This has happened in all six of the M&Ps I've owned. In some, the slide movement changes the sight picture whereas in others the sights remain aligned throughout. 
This begets two questions

1. Do Performance Center M&Ps demonstrate this behavior too? Am asking because I don't know whether it's a function of loose part fit and barrel lock or large striker mass compared to reciprocating mass (slide etc.)
2. Do any other striker fired pistols demonstrate the same phenomenon? I've owned striker fired Glocks, Sigs and CZs, and none of them seem to do this.

[Archangelgt]

P320s are notorious for this. The slide will lift in the rear significantly when dry firing, changing your sight picture. For P320s if you dry fire with a magazine it normally goes away. Some I've found you have to dry fire with a dummy round for their to be enough pressure to to stop the lift. 

 

On my M&Ps I never thought it was so bad I tried to remedy it. Give a magazine, or possible a magazine + dummy round a try. 

[Jhp147]

My 2006 M&P is so bad about the slide angling and sights shifting left to right when the tension comes off the striker/sear that it discouraged dry fire.  I've wondered if a newer locking block with less generous tolerances was ever available or if a newer one would help.  I have a newer striker and large spring sear block installed.  It is not nearly as visible in my later models, but they are .45.    

[SteelCityShooter]

Both my 5" M&P9 2.0 pistols do it slightly.  One is an standard 2.0 and the second is a Pro Series CORE.   However the movement is so slight that it has no noticeable effect on the sight picture when I dry fire even with a red dot which should be more sensitive than iron sights.

[P Taylor]

It is the striker spring holding the slide a bit, on my M&Ps if I give the slide a push forward with my thumb after resetting the sear the slide does not move when the striker falls.  I am not a competitive shooter and use heavy .40s for carry. The heavier recoil spring for the 200gr 40s also helps to seat the slide so I would guess if you are using a lighter recoil spring with 9mm the problem is worse.

[hlsccsfa]

I have also observed the same thing with all 4 of my m&p 2.0, 1 regular 5"FDE, 2 performance center pro core, and 1 4" compact. I am sure it doesn't affect its accuracy whatsoever. 

[Lior]

Thanks all for your reassuring responses!

[MemphisMechanic]

Stuff a mag full of dummy rounds and insert it. The upward pressure on the slide helps somewhat.

 

But. All striker fired pistols do this. The mechanism is a tug of war between the recoil spring and the striker’s cocked spring. Roughly 17lbs forward and six pounds rearward, before we swap to aftermarket springs.

 

When the shot is fired, the striker is released and all rearward pull vanishes, along with the striker hitting the breechface and tapping the slide forward. Things shift. It’s fine.