The M60A1E4 was a conceptual variant that explored using different remote controlled weapons, which include a 20mm gun as secondary armament. A mock-up of the design and style using the Type C turret was built. The second era experienced enhanced night-fighting capabilities and normally nuclear, biological and chemical (NBC) safety. https://hoytmachineguns.com/product/ingram-m11-m11a1-380-acp-small-frame-mac-powder-springs-ga/