If you want to rank up more quickly than you currently are in MW3 multiplayer, this page by GamingUpgrade is by far the best resource to use. It's long, but if you plan on prestiging once or more it's pure gold.
Here are some gun stats.
This page by Symthic has the best presentation of all the gun stats you could ever want. Take a minute to browse through it and you'll be as impressed as I was.