The M60A1E4 was a conceptual variant that explored the use of a variety of remote controlled weapons, which includes a 20mm gun as secondary armament. A mock-up of the style and design using the Type C turret was manufactured. Following First exams with only the new engine and suspension, extra https://hoytmachineguns.com/product/new-in-box-factory-colt-m16a2-model-r0977-m4-carbine-safe-semi-auto/