I recently read a review about another rifle in which the author states, “eliminates potential slam-fires, a problem with AR-type rifles”.  Sure, there firing pin is not blocked or restrained in the bolt.  However, as I understand it, there is no way an AR can slam-fire unless the firing pin is obstructed and stuck in the out position.  Hence, the author’s statement sounds like BS to me.  

Is this writer making up problems with the AR to hawk the new product?  Alternatively, does the AR platform really have an issue with potential slam-fires under special conditions that I am just not aware of?  Has any one here actually witnessed an AR slam-fire before?  If so, what caused it?

Only two things as far as I know:

Obstructed firing pin caused by filth in general thus hindering its movement.

or

Soft primers on commercial ammo, judging by some often-mentioned questions to the ring of "Why does my unfired but chambered round have a dent in the primer??" and the usual soundings regarding military primers being much harder.   In other words, some commercial .223 may go off upon chambering... I don't recall an account of this actually happening tho... myth, perhaps?


my .02, correct as needed.

- BG

Third possibility:

Repeated rechambering of a round.  There've been reports from Iraq regarding slam-firings when troops were loading their rifles using rounds that had already been loaded and unloaded numerous times (they're required to clear their rifles when they enter secured areas).  Some may be due to carelessness, but at least a few are definite slam-fires, witnessed by others, to include a sergeant major in the safety message I saw...

I have had fed primers go off when I drop the bolt on them,  all hand loads - I believe the problem was I wasn't bumping the case back far enough in the sizing operation.   I stopped using fed primers in my AR's  and changed the sizing operation to match the chamber and started using cci primers.  I haven't had any problems with factory loads.

Rare.

Maybe the author of the book only had experience with M-16's during the Viet Nam War, when people blamed everything they could on those dang new-fangled mouse guns.  Slam-firing was a fairly common complaint then, and resulted in harder primers and lighter firing pins.  I think.