Abstract A method of forming rifling, including that of a gain twist configuration, by the chemical milling process in the bore of a barrel which may include a liner of a refractory material. A template rod made of an acid resistant material which is radially compressible and which has a diameter slightly greater than that of the bore is pressed thereinto so that liquid tight contact is made between the surfaces of the rod and bore. A plurality of spiral channels and uninterrupted areas are formed in the rod to image the desired rifling configuration. A closed circulatory system delivers fluid acid to one end of the channels, and the rifling grooves formed thereby, and after passing therethrough returns the acid to the pump for recirculation. A pressure gage between the pump and barrel may be used in lieu of an elapsed time for chemical reaction to indicate when the rifling grooves are formed to the desired depth.
The invention as defined in claim 1 and including the steps of installing said barrel in a closed, liquid circulating system, pumping said acid to one end of said bore for passage through said channels, and removing any foreign solid matter and the gases generated by the chemical milling process from said acid before being returned to said pump for recirculation.
Claim 2
Dependent Claim
63 words
The invention as defined in claim 2 and including the steps of adjusting said pump to a specific pressure output, gaging the pressure of said acid as supplied to said barrel, and comparing the pressure gaged to that determined as being the pressure of the acid to the barrel according to the adjusted pressure when said grooves are formed to the desired depth.
Claim 3
Dependent Claim
42 words
The invention as defined in claim 2 and including the step of stopping the erosive Action of said acid on said bore surface after a period of time predetermined as being sufficient for the formation of said grooves to the desired depth.