Mine is a 1975 Wingmaster 20ga. Slickest pump I've ever shot. Came with a 28" fixed Mod choke and a 26" fixed I/C choke. Both barrels have no VR.
Maybe someone here can answer this: Why some early/mid '70's Wingmaster's have no rib, others do? Doesn't seem to bother me, curious tho. Mine is 2.75" shells only, and is built on a 12ga receiver. Still use it for dove.