Helloooo Community! 
I for one am one who likes to have alll of the numbers and statistics for things, I am an odd one who like to calculate and know everything. So many years ago I came across this link and I have always referenced it,
http://www.zombiepanic.org/forums/showthread.php?t=8068
As time has passed though, new updates have occurred and new weapons have been added and adjusted. I wanted to give everyone a chance to see this, and perhaps offer a community project to update and maintain this list for all to use. The information for how each stat was determined is pretty well spelled out if you read through the link. I hope that a couple of people who are really serious and detailed about these kinds of things would be up for taking the time to finish it and keep it here on the forum for any player to see
LOVE and PEACE Everybody!!!!