I am reading all the mags my Dad sent with me, but can anyone recommend a book or a website that can give me some good basic knowledge on firearms and ballistics? Something like "guns for dummies" would like to understand the cal. vs. mm vs. .###. Really bugs me that I dont know this stuff. Like why is it a .45acp if it isnt just for a colt? I am sure these questions are silly to you all, but I am serious about leatning all I can.