The model 4 savage has the knurled knob at the back of the bolt but it is not the tube feed, it uses a magazine clip. The model 5 was the next model which added the tube feed in place of the magazine clip and has the knurled knob at the back of the bolt. Look at Item # 105020058 on gunbroker.com. This is a model 4. Take away the clip and add the tube feed and you have the model 5