Magazine Well

• Riser Rebuild
• Final Fit

Riser Rebuild

The "riser" is the area immediately below the ejection port that HK has molded in such a way to disallow HK G36 magazines from insertion:

This effectively forces you to cut a notch into the riser when converting to the TN / BMP AR magazine well conversion, or if you wish to use G36 magazines again.

You can choose to either mill (if you have access to a mill) or dremel the notch.  I used a mill, but if I were to do it again, I would use a dremel and a cutting tip.  The mill vise (or clamps) can too easily scratch the soft surface of the receiver, and set-up time is rather long for such a trivial job:

No turning back!

The rear area to be cut out:

Cut out all along the left side and the rear area.  You will remove more material than you may expect.  Go slow and check your progress often.  Stop when the magazines fit easily and fall free when the release is activated.

The outcome:

Final Fit

The TN / BMP AR Magazine Well conversion uses a synthetic magazine well that fits, but may require some tweaking.  I found that the retainer pin was too tight and so I polished out the hole with a dremel cutting bit to open it up slightly:

This made a world of difference!  The magazine well now assembles without killing your thumbs.

The TN / BMP conversion has a rather thick reinforcing spine on the back.  This spine prohibits function of the original magazine release lever.  I milled this spine down until the magazine well would fit without the need to remove the magazine release lever.  I didn't mean to step the cut, but I stopped once enough material was removed:

Finally, the original magazine release lever can be left alone!  It still doesn't release the magazines, however it does serve to brace the AR magwell and make the front-to-back fit much more snug.

I'm working on a quick-release lever for the AR magwell... stay tuned!