I have examined some web postings on this topic and am still baffled by Wolf's statement. From what I can tell, the S&W M&P-15 is an standard AR15 type action. Stoner designed an action in which the firing pin is positively blocked until cam down. This is different from the Garand mechanism which the free floating firing pin is free to impact the primer virtually throughout total bolt movement. There are lots of reports of in battery and out of battery slamfires in Garand mechanisms. This mechanism relies 100% on primer insensitivity to prevent an inbattery or out of battery slamfire, because the firing pin is able to make incidental contact with a primer, prior to cam down. And the free floating firing pin will rebound of the primer, once the bolt is in battery. This image of of a M1 carbine receiver, which is functionally similiar to a Garand, probably easier to mill the firing pin cocking cam:
However, to reiterate, Stoner's action, the firing pin cannot go forward to touch a primer until after cam down:
But, you can still have "out of battery" slamfires in AR's. And from what I have heard, it is due to bolt bounce. Reports of in battery slamfires with AR's are surprisingly common, I saw one, I had one. The theory I heard, and believe,for an out of battery slamfire to occurr, is that the bolt carrier will bounce back, unlocking the bolt. And, before this happens, or maybe as it happens, the firing pin has bounced off a sensitive primer which ignites. With the lugs out of battery, things can get very messy.
So, if factory ammunition is out of battery slamfiring in an AR15 mechanism, that is not the fault of the mechanism, it is a fault of the ammunition. That is, the round was loaded with primers too sensitive for safe operation of the weapon.
So, I cannot see how Wolf's warning is accurate at all.