I could be missing something obvious here but...
I realize that guns have various calibers. I have a few questions:
1) Why is .40 called .40 S&W? Did Smith & Wesson "invent" this caliber?
2) Why does ACP follow .45 so often?
3) 1911 is a reference to the Colt 1911 pistol, right? Was this "frame" originally made in 1911? If yes, are all the 1911s made today just updated versions of the Colt 1911?
4) When you say you have a 1911, does it use a particular size/caliber bullet? Or is there a 9mm 1911?