Here's a how-to on switching or taking off the Vang Comp System Sling Mount on their Magazine Extension Tube:

Tools:

C Clip removal tool


Instructions:

1) Remove C Clip from mag tube by expanding the clip and sliding it off.


2) Remove Sling Mount by sliding it off also.


3) If you are removing the mount, you can now reinstall the extension. Otherwise, flip the mount around.


4) Reinstall the C Clip and then install the extension.