Home Projects Realcap Converting Low-Cap Tokyo Marui AEG Magazines to Real Capacity

Converting Low-Cap Tokyo Marui AEG Magazines to Real Capacity

by Arnie


Converting Low-Cap Tokyo Marui AEG Magazines to Real Capacity
by WMH

WMH Custom Tokyo Marui M16 RealCap Mag (externally identical to Low-Cap mag) 

Parts Used:Tokyo Marui Standard M16 Series Magazine (Low-Cap)Small Screw from Toyko Marui Tracer Unit (or anywhere you can find it)


The Tokyo Marui Standard M16 Series Magazine (popularly known as the TM Low-Cap) holds 68 BBs. It is however, a replica of a 30 round M16 Magazine. This guide will show you how to correct this error in realism.

This modification is based on an age-old concept. Here in the USA shotgun capacity is limited in certain types of hunting, and I’ve seen hunting shotguns come with magazine limiters — in the form of a wooden dowel, which inserts into the magazine follower and physically blocks capacity. This is what we will be doing here, using a small screw to physically block the magazine spring.

The screw that you need is a small one, you probably already have one lying around. This screw needs to have a small head, but enough length to fully block the magazine BB follower spring. The one used here is from the TM tracer unit, which comes with several screws for the different adapters, and they just happen to be the perfect size for the M16 series inner magazine width.

Originally, I did this modification by completely dissasembling the inner magazine, cutting down the magazine follower spring, and inserting a screw to block the spring end-part. Then, I realized this was not needed.

All that needs to be done is to block the spring itself, giving it just a bit of room to compress when full of BBs. This is a much better solution, as you can reverse this mod by just removing the screw, regaining the original capacity of the mag.

And while this guide is based on the TM M16 Series magazine, it can be applied to any Low-Cap or Mid-Cap mag where the inner and outer magazines are separate.

Step 1: Remove inner magazine from outer magazine by pushing in plastic tabs (see photo). It is a good idea to use popsicle sticks or something similar to avoid damaging the finish of the metal outer mag.

Step 2: Locate where you need to put the screw. You want your screw going into the center of the BB channel. It is hard to see in the photo, but on your mag you’ll be able to see where the molded BB channel comes down from the feed spout, around the bend and winds around. The location you put the screw along this channel will determine the capacity of the mag. It goes about (see picture) there.

Step 3: Sink the screw. You’ll need a pilot hole (which must be smaller than the threads of the screw). I actually melt this hole using a tiny jewelers screwdriver heated for just a few seconds (melting point of ABS is very low). This is to avoid any shavings from drilling that would end up in the mag which we do not want to dissasemble for cleaning as it can be a pain to get the spring back in. And you don’t want those shavings in your mag as they may end up in your gun.

Ideally, you want the screw to thread into both sides of the inner mag, so melt your pilot hole accordingly — a little bit into the backside.

Note: If you do not get the screw in the center of the BB channel, you may experience a malfunction in that the spring will — under compression — move past the limiter screw, then not return the follower all the way up. This can be corrected by ‘snagging’ the spring with the screw.

Step 4: Test Magazine by fully loading and unloading (by depressing BB release catch in feed mouth of mag). I do this three times. Count BBs to verify correct capacity by unloading into large plastic bag. If spring slips, refer to step 3. Holding fine? Reassemble Magazine!


Project Complete!: Enjoy your new RealCap magazine! If later you wish to return to original capacity, remove the limiter screw (and cover the screw hole with tape).

External links: Links to external sites of interest.



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