The M60A1E4 was a conceptual variant that explored the usage of numerous remote managed weapons, which include a 20mm gun as secondary armament. A mock-up of this style and design using the Type C turret was built. The barrel latch mechanism (a swinging lever) could catch over the gunner's devices https://hoytmachineguns.com/product/lot-349-u-s-saco-m60-machine-gun-class-iii-nfa-fully-transferable/