Abstract: A method of modifying a rifles of the M16, M4, AR15 platform provides a second bolt stop release operable from the right side of the rifle. The second bolt stop release is a rigid extension of the bolt stop that passes through the right receiver wall to a position accessible to a user gripping the rifle with the user's right hand in conventional firing position. The two bolt stop releases provide the inventive rifle ambidextrous bolt release operation.

Abstract: In an electrical circuit assembly a stack of modules is secured in a bore through a casing, there are longitudinally extending grooves in the internal surface of the casing, and electrical interconnections each have a part both extending from a module and protruding into a groove, and a part in the groove. The electrical interconnections, the constituent electrical interconnection parts, if initially separable, and possible insulating members in the grooves between some electrical interconnections, are secured, and required electrical connections are made, by these circuit assembly parts being clamped together in the grooves. The stack may be clamped in the bore. The clamping means may include end covers for the grooves and/or for the casing bore, and the end covers may be in resilient engagement with, respectively, the electrical interconnections, and/or the module stack.