Cast is extremely easy to accurately measure in your shop with about 10 cents of material. All it requires is a vice to hold the assembled gun, A small accurate level to level the gun, a string with a small knotted loop on one end to hook over the front bead and a plumb bob or any small weight on the other end of the string. After leveling the barrels hook the string over the front bead and extend it along the exact center of the rib to the end of the butt and use a nail above the butt to raise the string slightly above the rib so it isn’t touching and then the weighted string hangs over the end of the butt. When all movement of the weighted string has stopped look at the string’s relationship to the buttplate and measurements are easily taken—both cast at heel and toe.
(To set the level I lay two short sections of 1/4” to 3/8" metal rods beside the breech end of the barrels, one on each side of the rib, and set the level on top of the rods. That provides a stable base for the level.)
Clear as mud? Wish I had pictures of the process, it is incredibly simple. Try the concept and you’ll quickly figure it out.
