Patent GB-148826-A (GB)
Title: An improved method of and apparatus for testing and truing rifle barrels and similar objects
IPC: F41A31/02
Filed: 1920-07-10
Abstract: 148,826. Marcuse, A., and Wanschaff. H. April 27, 1916. [Convention date]. Small-arms.-In a method of testing and straightening rifle barrels and like objects the image of a mark in a telescope situate in the axis of the barrel, as reflected from a mirror fixed at right-angles to the axial direction of the barrel on a support guided therein is brought into coincidence with the image as seen through the telescope. A telescope C, Fig. 1, fitted with object glass W, cross-wires S and eye-piece E containing reflector x is clamped to a barrel B rotatably mounted on supports 0 in such a position that its axis is in alinement with the true axis of the barrel. Parallel rays of light are projected into the barrel against a plane mirror A by the object glass, reflector and lens F from a source G. The mirror is fixed to a block Z provided with a leaf spring X and connected to a rod K which is attached by a cross-bar Y with ball-joint U to a. rod L secured to straightening-apparatus D carried by a. slide P. The red K is free to rotate in the cross-bar Y in accordance with the rifling of the barrel. The slide P is traversed by a rod J near the operator either direct or by worm &c. gear. The mirror and straightener are first fixed at the breech end and the cross wires adjusted until they correspond with the image thereof as reflected from the mirror. The centre and muzzle end are then tested and any displacement of the object and image showing a bend is rectified by operating the straightener through bevel gear H rotated by a handle Q<1>. Intermediate portions may also be similarly tested and trued. The testing and straightening means may be separate if desired, and in this case the rods K, L may be graduated. The Specification as open to inspection under Sect. 91 (3) (a) describes other forms of apparatus for this purpose. In one form in order to facilitate changing of barrels and to protect the telescope during straightening particularly when operating on machine-gun or other thick barrels, the telescope may be fixed separately from the barrel. In this case a plane-parallel glass plate is secured to the end of the barrel and the telescope attached thereto so that the cross-wires and the images as reflected from the glass plate and mirror coincide. The barrel in another form may be arranged vertically. In another modification, Fig. 3 (Cancelled), in which the breech end is stronger than the muzzle end, the extra pressure required in straightening is obtained while the same pressure is exerted by the operator by pivoting the hand lever a to a pin d carrying a roller arm e which engages a spring-controlled lever b carried by a slide h. The lever b operates the spring-controlled cams f, g so as to actuate two straightening-slides i, k which are returned by springs clear of the barrel so that accidental movement of the mirror is avoided. The slide may be traversed by rods or chain gear &c. In testing rifle barrels mounted on their stocks the bolt of the rifle is removed and replaced by a tube provided with a telescope similar to that shown in Fig. 1 except that the eyepiece is laterally arranged and the source of light placed at the end of the tube. The mirror is mounted on a block carried by a rcd inserted through the muzzle. The subject-matter of this last form is contained in Specification 168,065, [Class 97 (i), Optical systems &c.]. This subject-matter does not appear in the Specification as accepted.