I found this article in Gun Tests with some speculation from a reader and his findings about OOB mis-fires with the 15-22. I suppose what he says can be true but i'm not sure about his accusation that the firing pin cannot hit the casing sufficiently enough to set of a round when the bolt is not fully forward... ?

I have shot a video of the 15-22 firing out of battery with quite a substantial gap between the bolt face and the breech face. You can find my video at the top of this forum under the video sticky.

IMO based upon 50 years of gun work, 30 of which was spent as a civilian weapons trainer for the U.S. Army, I don't think you can fire a semi-auto .22 rimfire fast enough and in sufficient volume to effect a "cook off." Further more, a "cook off' would not occur during the cycle of firing but rather after firing was suspended and a loaded round rested in a hot chamber. It takes a few seconds to sufficiently heat the cartridge and associated propellant to effect the "cook off."

Cook off?! Nonsense.

The S&W M&P15-22 will fire out of battery. It's a known defect of the design and using the M16/AR15 fire control parts.

Yes, the firing pin strikes the case rim and detonates the cartridge primer. The case usually explodes and sends the extractor several firing points to the right.

Not sure who Winfield might be, but he shows an astounding lack of knowledge of cook offs and the M&P15-22 specifically. The cartridge is held securely to the face of the bolt by the extractor as it exits the magazine. If it's mostly in the chamber the bolt is far enough forward for the hammer to strike the firing pin and the rifle will fire out of battery. This occurrence is becoming less reported here than six months ago, but it still happens.

-- Chuck

nevermind... I need to read before responding!

Foot In Mouth

+1 No way 22LR is cooking off out of a semi auto with a 25 round mag..... Anyone paying attention to this gun knows it can and has fire OOB... No other explanation for the blown up ruptured cases and exploding extractors of which the pieces of are often never found.

Thanks everyone for your informative responses and they are as I expected. A cook off round just didn't seem feasible with the 15-22 and I agree, the round would have to be chambered for several seconds in which case would mean it was already in the closed bolt position.

This just confirms to not believe everything we read in our gun rags.

Amen to that.

GUN Digest The Magazine.
Issue: 2010 Shooters Guide
Article: BLACK GUN REVIEW 2010
Writer: Scott W. Wagner

Page 21 Scott writes: "The SIG522 will give a low cost alternative to those who favor the the SIG566 rifle as their black rifle of choice. Interestingly, the SIG522 has a hammer forged barrel, and operates from a modified gas piston system rather that straight blow-back." Again it is indistinguishable from the full power version unless one takes a close look at the action area, noting the small ejection port area and rimfire extractor setup"

Oh yeah...