[tet68]

Curious.
Are there many 31round mags?
I suppose it could have been
A 40??

[Talisker]

I think the standard choice is either 20 or 30 rounds for an AR, right?

[PLMerite]

“Are there many 31round mags?”

Chamber a round then replace it in the 30rd magazine. Then you are, as they say, “fully loaded.”

And fully stupid judging by the results this guy got.