Last week I was able to aquire a Ruger Old Army revolver after only recently (maybe a year) of becoming aware of them. It seems to be in exceptionally good shape, very clean and crisp. But, I was curious as to why the caliber is not marked on the gun? I was already aware of the required ball size and printed a copy of the manual off of the Ruger website to become as familiar with it's operation as possible, as the gun came only with a smile. I plan on some range time today to have some fun. I already have a couple of muzzle loading rifles so I am not a true beginner in this area of firearms, but I am new to the BP revolver. But again, why no caliber mark?