help identify this 9mm firing pin mark

[Jamie Green]

I've seen that happen on both some Sigmas and Kel-Tecs that have come through our office.  One Kel-Tec comes to mind where the firing pin impression was totally covered by the shear.

[Steve Scott]

I agree with Jamie...very KelTec-ish

[Zak Carr]

Last month I had a Smith & Wesson SW9VE (newer style Sigma) that exhibited this type of FP aperture shear all around with only a very small bit of the FP impression still visible.  This type of shearing was only displayed on my two Remington TF's... my Winchester TF's looked normal with only minimal shear right at the tip of the FP drag. 
Not saying that another make/model firearm couldn't leave a similar mark though...
Z.

[Aaron Brudenell]

Here are two examples of the same kind of thing:

The first is a pair of different .357 magnum ammunition fired in the same gun (Remington on the left) and the second is a pair of 10mm reloads also fired in the same pistol (primer type not known).

I've seen this "full aperture sheer" a number of times and while it's not always consistently reproducible, I have noticed it to be a lot more common with Remington ammunition and higher pressure ammunition.