I have been doing a lot of reading and looking at NFA gun boards and getting ready to make a purchase - I'd love a FA AK-47, but what little common sense I have tells me to start with something less expensive and I will probably go with some type of MAC - I'd appreciate feedback on a few questions. The main difference between a MAC 10 and a MAC 11 is that the MAC 11 is smaller and lighter - right? Ammo prices are certainly a consideration - from what I can see, at today's ammo prices, 9mm is the most cost effective round - right? Any specific manufacturers or configurations that are more highly regarded as far as quality? Any to avoid? I would like to be able to shoot 22LR through the MAC - it looks like there are a few different add-ons I could purchase to do this - would I need to have a gunsmith do this, or would the level of difficulty be like working on my AR-15 semi automatic? I'm not necessarily interested in a silencer, but I do want a longer barrel - does the longer barrel need to go on a separate Form 4? What MAC modifications would require a separate Form 4? Thanks in advance for any feedback.