Ignore what everyone else is saying - stay away from video tutorials!
I've never once found one that was anything more than time-wasting garbage.
Try here [http://www.tutorialized.com/tutorials/3DS-MAX/1] for some helpful text-and-picture tutorials (they'll teach you a lot more effectively).
I've been using Max for 4 years now, and although I'm not an expert, I've made a few good-looking things.
Maya is good, but whichever you learn first is what you're going to stick with.
Despite being made (currently) by the same company (Autodesk, the maker of Maya, bought 3DS Max from Discreet), they are extremely different in their interface, technology, and overall power.
If you want to decide which you want before you start, then go with this as a rough rule; Maya is easier to learn, and much easier to master, but once you do, there's nothing more you can do with it.
Max on the other hand is very difficult to learn, and even when you think you've mastered it years later, there's always something new for you to learn.
So, basically, Maya is easy to learn but more limited, Max is hard to learn, but is a lot more powerful.
As for the idea, it would be really cool for a game, but unfortunately it would never work in reality.
Wind, along with a host of other factors, would influence targeting, firing, and successful engaging of a given target, making it physically impossible for this to be an effective weapon.
A few of these would be:
[ul][li]Changing air currents[/li]
[li]Refraction of light off the outer atmosphere (making accurate targeting impossible)[/li]
[li]The lack of stability of a falling bullet, which would cause it to veer horribly off course[/li]
[li]Friction from drag, which would melt any metal (and possibly diamond - it only takes 4000°C)[/li]
[/ul]
P.S. If you want a really interesting example of what Max can do, look for a tutorial about using missiles to shoot teapots - the smoke and tracking effects are absolutely stunning.