The MAG AD9 is one of the most innovative AR15 accessories in a generation. It's what every other pistol-caliber conversion aspires to be. And it doesn't require any modifications to your lower receiver.
The MAG AD9 accepts reliable and inexpensive 9mm GLOCK magazines--which literally litter the landscape. Sporting inspired engineering and superlative execution, the MAG AD9 takes your favorite black rifle to some previously unexplored places.
BEGIN AT THE BEGINNING
Colt gave the pistol-caliber AR concept a whirl in 1982. The Colt Model 635 SMG used a modified M16 lower along with a custom upper that eschewed a forward assist in favor of a big rubber ejection buffer. The gun ran 9mm Parabellum from the unlocked blowback and was both handy and reliable.
The rub? The conversion required drilling holes in the lower receiver. That's not a big deal when the receiver began as a $40 homebuilt project. When it is a $14,000 transferable machinegun chassis it becomes another matter entirely! Additionally, the Colt gun used proprietary 32-round double-column box magazines adapted from those of the Uzi. It turns out there was a way to do things better.
THE MAG AD9
The beating heart of the MAG AD9 system is a drop-in magazine well conversion device that slides into place within the magwell of favorite ARs and adapts it to accept polymer GLOCK magazines. The adapter sports its own separate magazine release that's easily accessible on the right rear aspect of the magwell. The unit is secured in place via the host gun's magazine catch.
The MAG AD9's set screws excise any wiggle that might result from variations in tolerances among the many millions of AR receivers out there. One component is called a gib and snugs the unit fore and aft. Two nylon-tipped Allen screws put tension against the magazine catch and keep everything tight.
The MAG AD9 device has a built-in ejector and--literally --couldn't be any easier to manage. Installation takes maybe 3 minutes and removal about the same. Once installed the adapter accepts mags of any capacity. Standard pistol magazines are nearly flush with the bottom of the magwell while 33-round boxes give you plenty of on-tap chaos without undue bulk. Compact drums multiply the fun.
The Stern Defense upper receiver assembly provided for this project sports a short pistol-length barrel and a heavy-weighted bolt carrier cut for full auto operation if required. Everything was exquisitely well executed and nicely finished.