Mossberg Shockwave Taccom3g +1 Magazine Extension

[meanmotorscooter]

I just installed the +1 extension on my Mossberg Shockwave. It does not work reliably at all with the factory spring. I had to install a longer spring to make it work. It would also be nice if grooves were machined into the base so it would engage the factory magazine cap detent. The spring that actually works is on top. It now hold 7 2.75" or 10 mini shells.