Looking for a bore and shell length gauging tool

[Stan Hillis]

I have used nothing more than a 6" machinists scale (rule) for years. One can hold the muzzles towards a good light source and slide the rule slowly into the chamber, holding it snugly to one side of the chamber. You can clearly see the beginning of the forcing cones. When the rule touches the beginning of the forcing cone, look at the scale and get the length.

I know this sounds like a shadetree procedure, but once you try it you will find it to be very accurate and repeatable. Besides that, the "store bought" gauges are not entirely accurate because all chambers in any given gauge, from model to model, are not uniform. Super Fox guns' chambers, for example, cannot be measured with over-the-counter gauges. Tapers vary in the chambers of these old guns, so one with a tight chamber will not read accurately using the brass drop in gauges.