When designing the AR-15 pistol caliber carbines and upper receiver conversion units, enough thought was given so as to engineer a system that would be able to work on any standard mil-spec .223 cal lower receiver without modification to the lower. To do this, all the conversions and system changes had to made to the upper receiver units and magazines only.

Magazines for the pistol cartridges had to be chosen in such a manner that would be complimentary to the system. First off, they had to actually "fit" inside the physical space of an AR receiver's mag well. This presented limitations on some mags designs, and eliminated many of them right off the bat.

Uzi mags were chosen because of their legendary reliability. Also, they are still (belive it or not) readily available at fair prices. Additionally, they are a great fit in the AR lower. These mags were also very versatile as we are able to adapt the Uzi 45 ACP or .41 Action Express mags quickly and easily to work with the 45 ACP, 40 S&W;, and 10mm cartridges. Three birds with one stone so-to-speak.

Sten Gun mags were also a great fit in the AR lowers, are very inexpensive, and there are quite literally TONS of Sten mags (new in their 50 year old wrappers) still available. The world may never use up all of it's inventory of Sten mags.

These mags were chosen, then had to be modified to work. Initially, a 2 piece system was used which incorporated a separate magazine well "block" with a lever/toggle lock on the back of it. The mag block insert was held into place by the standard AR-15 magazine catch, and the block's lever served as the catch for the Sten mags. This worked really well, but the average consumer wanted little to do with a 2 piece mag system.

Complaints poured in about lost or stolen or damaged mag blocks. Once these mag blocks were either not available because of loss or theft, or were damaged beyond a level functional reliability, the whole rifle system was deadlined. A pistol caliber carbine could not be used without that mag block. It because just so much metal. Additionally, police and military units required re-training because of the new mag release button. Generations of cops and infantrymen were dropping their entire magazine system (block and mag) right out on their toes every time they hit the standard AR-15 magazine release button. When lives were at stake, this did not sit well either.

So, here we are with today's one piece magazine system. First the 9mm Sten mag.

The mag block (seen at right) is actually a piece of steel square tubing that is cut to the proprer length, machined with a mag catch and then welded to the mag. At this point the magazines are completely dis-assembled, cleaned, bead-blasted, and then re-parkerized to give them the best "as-new" appearance we can give. This also assists in the proper functioning of the magazines.

Sten mags are used exclusively for the 9mm conversion system.

The converted Uzi Mag as shown here, is done in essentially the same manner. Uzi mags (also a steel magazine) are acquired, fitted with the mag well block adapters, cleaned, refinished and reassembled.

The Uzi mags, because of their versatility, are used for the 45 ACP, 40 S&W, and 10mm conversions. We use both 45 caliber and .41 Action Express (a little known yet very powerful and effective caliber in its own right) caliber Uzi mags for these conversions. In the case of the Uzi mags, some modifacations are made to the magazine shape as well as the feed lips to accomodate all three calibers.

Hope this helps top answer your questions. As always, if you need more information, please feel gfree to call us at 800-228-3471.