The Beretta Model 92/M9 9 mm magazine holds 15 rounds. It's a simple matter of physics. Inside a given pistol magazine, there is only so much room or area for the cartridges, the magazine follower and the magazine spring, right? Sure you can make the wire spring compress inside itself or add a bumper that will allow maybe an extra round or so, but that's about it, correct? Not anymore, thanks to a new Mitchell's Mausers magazine for the Model 92/M9 that can hold 20 rounds in a magazine of the same external dimensions as a factory unit.
The key is a small, clockwork spring pinned to the magazine body at its top that rests under the follower and unrolls itself as tension is increased. The spring takes up less room, provides constant tension from the first cartridge to the last, and the magazine actually still functions with its polymer baseplate removed.
Best of all, the last round is no more trouble to load than the first. Company founder Don Mitchell (before he went into the Mauser business he was an old hand at Colt and High Standard) told me about the prototype years ago, and I didn't believe him at first. Now I do, as I have used the stainless steel unit in a Beretta Model 92FS, and found it functioned flawlessly. It was easier to load the last 10 rounds in the Mitchell's than it is the last five in a standard magazine. A well-thought-out loading tool accompanies the magazine, but I found I didn't need it at all. This magazine is the subject of four patents, and in addition to the 92, is available to fit the SIG Sauer P226 and the Springfield XD. www.mauser.org.