haha, its only a teeny bit of dremeling... just shaving one section, and drilling a small hole. cutting the spring to the right length was the tricky bit.
Thought we had screwed it up when we tested at the end, realized after I got home that the reason the charging handle wouldn't release the bolt was because the mag was still empty, so of course the bolt stays locked.... Put a bb in the mag, and it worked perfectly. :-)
UPDATE: Check it out -->
Lm4 charging handle mod - YouTube