MP5 HPA Adapter for Mk23 Marui/STTI

Hello !

Here is an MP5 Mag Adapter with an HPA supply, for the MK23 by Tokyo Marui, or the STTI Clone. This part has been modeled around the STTI Mag, you need to check if the mag of the Marui has the same bottomplate (technically, it should).

You'll need :
1x 6mm PTFE hose of the lenght of your choice
1x 6mm Macroflex of your choice
Silicone/Gel glue (Shoegoo works really nice)

It works really well, the only trouble you can get is to have a proper seal. Since it's heavily dependant on the quality of your print, your settings, the porosity of the material, I recommend that you do the same as me : you apply a layer of glue on the top of the print (and around the PTFE tube) to make it impermeable. To be sure to get a nice seal, I recommend you put a thick layer of silicone (or glue, but the silicone is easier if you ultimately want to diassemble the system) where the stock oring is supposed to be, assemble the system, and let it dry long enough (for silicone, itcan be several days, just remove the percussion valve to let an airflow). I had a perfect seal by doing this.

Insert the 6mm PTFE tube in the hole and let it go further a bit. Glue the outside of it to get a good seal.

When printing, first try the "improved" version. This version is adapted for a fully 3D printed adapter body, with the feed tube being included and thicker than the standard one. Print it like the screenshot, when tilted like this you will only need supports on the feedtube. The layer orientation will make it really strong.

If it still isn't strong enough, i included a version with a hole for a metal feedtube (the one I made). You will need to cut down an old barrel (just take an old aluminium or brass one) to 15mm, and insert it by force inside the hole. Just make sure to chamfer well the edges.

If you encounter some feeding problems, this can be caused by the transition from the mag to the feeding lips. The small cut on the feeding lips can sometimes block the bbs and affect the feed. The file "mk23_single_stack" converts the mag from a double stack to a single stack, and greatly helps the feeding. Print and glue the part inside the bb path, on the side where there is a cut on the feedlips (with the small tab of the part covering the cut). Don't put a lot of glue, 3 drops of Cyano are more than enough.

You'll need to add a small 5mm spring for the release lever, or just find a pen spring and glue it in place.

Here's a shooting video : https://youtube.com/shorts/Z69AbNIkq_Y?feature=share

Have fun !