Firing Pin Question

[Submariner]

Which has the larger flange: M16 or AR15?

ETA: I forget. Oldtimer's disease.

[Nitrox]

M16

......

[Ned Christiansen]

AR15.

OK Nitrox, we arm wrestle.

I say the AR has the larger one as it was part of the changes made to make the semi-auto harder to convert. The larger flange snags the step in the hammer face better if a BillyBob does something to disable the disconnector.

[Robb Jensen]

A M16 (fully shrouded) or shrouded AR15 carrier will run with either firing pin.

[K.L. Davis]

the match goes to Nitrox...

M16 = large collar

[durka]

the match goes to Nitrox...

M16 = large collar

Agreed.

Colt sporter firing pin flange = 0.325" in diameter

New production Colt 6920 (standard M16 bolt groups) firing pin flange = 0.375" in diameter.

[Hoplophile]

AR15.

OK Nitrox, we arm wrestle.

I say the AR has the larger one as it was part of the changes made to make the semi-auto harder to convert. The larger flange snags the step in the hammer face better if a BillyBob does something to disable the disconnector.

That was my first thought, but now that I think about I'm pretty sure he's right. If you put an M16 pin in an unshrouded carrier and have a notched hammer then it can catch during normal cycling. You need to use the AR15 pin with the smaller collar so that the weapon will cycle correctly and the hammer will only catch on teh collar if it's actually free of both the disconnector and the primary sear.

[Nitrox]

OK Nitrox, we arm wrestle.

When I turn my hat around backward it is like flipping a switch...

[Ned Christiansen]

So.... the flange diameter was reduced for the AR, to reduce the snagging of the notch in the hammer to a level where the gun would still function?

[K.L. Davis]

So.... the flange diameter was reduced for the AR, to reduce the snagging of the notch in the hammer to a level where the gun would still function?

Baically... Yes.