Murray also adopted the Rollfast sprocket design, it was a popular design even back to prewar balloon tires like Elgin, etc. Bikes made by many makers came with it up until at least the eighties. Here's a red band hubbed murray from the early to mid sixties.,,,,BD

Murray drops with points though. It is possible his frame is a Rollfast, just saying many makers used that style of sprocket for many years.