If you include cannon in guns, the largest was the Tsar Howitzer, that had a bore diameter of 35 inches which means it is a 35 caliber cannon. (A .22 rifle has a bore diameter of .22 inches not 22 inches.) If you mean shoulder firearms, then the 4 guage shotgun may be the largest- although there were very large bore Paradox guns. In rifles, the German 20 mm antitank rifle of WW I (about .80 caliber) For sporting rifles, possibly the.700 Nitro Express.
.500s&w
The .950 JDJ is the biggest rifle The biggest hand held gun is the 600 Nitro Express Pistol
The BATFE web site has information that can assist you in answering your question.
Of course not. .50 caliber weapons are.
the 12 guage is a caliber not a gun
a .45 caliber.
What caliber of man are you looking for? What caliber of gun are you looking for?
there is no world wide data base.
The short answer is no. The longer answer is, you might be able to get a .40 caliber cartridge to fire from a .45 caliber gun, but it may damage the gun, and even if it doesn't damage the gun, it will cause other problems. In general (with only a few exceptions) you should never try to fire any cartridge in any gun other than a gun designed for that caliber.
It is the standard .68 caliber
Caliber has nothing to do with it.
smaller the number, the smaller the caliber.