This magazine by Tokyo Marui is a replacement for the factory 50-round magazine that comes with their MP5 AEGs. This particular model holds 200 rounds, which is handy, but there are some negatives to this design.

Appearance

  This magazine looks much like the TM standard MP5 mags with the exceptions of the top and the bottom. The top is not a major concern since it's usually concealed inside the gun, and the differences there are simple - mainly there's a loading door aft of the BB feed tube. At the bottom of the magazine is a winding wheel, which is the most noticeable difference between the hi-cap and standard mags.

Function

  Here's where the big differences come into evidence. With a standard magazine, you just fill the loading tube with BBs, stick it into the feed tube on the magazine, press down on the plunger, and your magazine is loaded and ready to go. Pretty simple, but all you get is 50 rounds in the standard MP5 mag. With the hi-cap mag, you open the door on the top of the mag and pour in around 200 BBs, more like 220 or so. Then you shake the mag up and down slightly as you wind the wheel on the magazine's bottom. Once you've got the spring wound all the way, the wheel will click if you keep winding. After this is done, you can pour a few more BBs into the hopper. Insert the magazine into the MP5 of your choice - for my tests it was TM's MP5A5 - wind the wheel fully again (since when you insert it you release the tension on the BBs and the spring unwinds a bit), and go for it.

  The magazine works well as long as you keep this in mind: You have to wind it back up occasionally during firing. Otherwise the spring runs out and you may be forced to wind it up all the way at an inopportune moment. By my estimations, you can usually get around 40 BBs out of the mag before it needs winding again. If you can keep it wound for the whole magazine, you're in good shape. What I did was fire a few bursts, wind the spring back up, fire a few more bursts, etc. When the magazine is empty, you'll hear the spring unwind all the way by itself, which is a distinct sound. In reality, the magazine still has some BBs in it, but not enough to reach the top of the feed tube, which is why you want to load as many BBs as possible into this thing.

Tactical advantage: Obviously, the quadrupled magazine capacity.

Tactical disadvantages:  The magazine rattles, since all your BBs are loose in the hopper. You have to keep the spring wound until the magazine's empty, which can mean rewinding it four or five times during each use in the gun. I don't know why they weren't able to design a feeding system that didn't need to be actively maintained during the firing process. It seems like they could have had a more efficient spring or somesuch that would allow for the firing of all 200 BBs with only one winding.

Overall Impressions

  The hi-cap mag is a useful tool for outdoor skirmishing where the noise of the BB's rattling is not likely to give your position away. It's gravity fed so you can't do anything wild like firing while hanging upside down out of a window. The spring needs constant winding (every ten to thirty shots to ensure proper functioning), and that might be a bad thing unless you were going against single opponents in dispersed locations where a couple bursts at a time would do the trick. Above all, these things are Expensive. Notice the capital E. Suggested retail for the MP5 hi-cap is over $100, however they're usually available for around $75. Still, when you think that a standard mag is half that, you almost want to take the quiet reliable simplicity of two standard mags and just conserve your ammo a bit.