It's obvious that I have no experience with the +2 round grip adapter-I just spotted the offer on Midway's site and after reading the description (interpreting it wrongly, it seems) assumed it added capacity to the Model 4006. From what you're saying, am I to understand that the mag in question won't work in the 4006? If not, I'll have to return the darn thing because I ordered one for my Model 4006...bummer!