Caliber and Cartridge

Question
Hello, Dave.
This must be tough on your part when you get letters like this. Here it goes. It seams I can not get any explanation about caliber, cartridge and diameter. Here is what I mean. What's the relationship of caliber to a diameter? What 8, 9, and 10mm caliber cartridge refers to? what does .58 .38 .50 .22 mean?

When they say that 22LR case is .223/.224 and the 22 Mag case is .230/.240. What's .230/.240?

Is there some sort of a table that can enlight me. A table that would have combined info for different Magnum, Luger, Supper-X and others, similar to a 'computer for dummies'.
Thank you much,
Allen

Answer
although this is outside my remit - basically (mm is abreviation of millimetres, whereas inches are all quoted as.50 or .22 etc) and the sizes quoted are the diametres. Hence .50 is half an inch diametre.

for example - a .177 pellet is the same as a 4.55mm pellet.

hth

dave