Tried like crazy to find something about this gun that bothers me.
Take the barrel off and measure from the cylinder face to the end of the arbor. Then measure the hole from the bottom to the the end of the forcing cone.
Just read on another site that the arbor difference can be measured by removing the cylinder, and pushing the arbor into the arbor hole until it bottoms out (the barrel assembly has to be rotated at an angle so the frame doesn't stop it from bottoming out). I measured the arbor being .068" short.
___________