The SR-47 is an outgrowth of the Colt M4 Carbine's SOPMOD system. Originally it was going to be a drop-in series of parts to convert an M4 or M16 in the field to fire 7.62×39mm ammunition. This requirement was later changed to require the weapon to accept and feed from Kalashnikov magazines. The complexity of this task made the planners rethink this approach and the idea of a complete weapon that could still use standard SOPMOD accessories was born.