Why do gun-makers make handguns, especially revolvers, in such odd barrel lengths? There has to be a good reason for making barrels 1 7/8 inches instead of 2 inches. Or 3 1/16 inches instead of 3, or 4 5/8 instead of 4 1/2. Etc. I tried converting the lengths to millimeters, and they come out in odd fractions there, too. I do understand the recent Ruger revolvers with 4.2 inch barrels - they're making sure they can sell them in Canada. But the others seem just plain weird. So what's the purpose of making those odd lengths?