The Firearms Blog has a post on a patent filing from Magpul Industries for a so-called "quad-stack magazine." Basically, as TFB puts it, the slightly wider magazine accomodates what looks like ...

Offering unprecedented capacity for a semi-automatic rimfire pistol, Kel-Tec’s new CP33 feeds from innovative quad-stack detachable box magazines that hold a total of 33 rounds of .22 Long Rifle.

But the star of the show is undoubtedly Kel-Tec’s recently-patented, transparent, jumbo-sized “quad stack” magazine that houses a whopping 33 rounds. If that’s not enough, Kel-Tec is ...