Unless your Spencer has a Stabler cutoff, you either have one in the chamber before you start, or you will have a loaded round trying to get in with that first one you are single loading. Doesn't sound real safe to me. If you have the Stabler cutoff, you can hold the magazine rounds in reserve, and single load for the additional ones, then finish with the magazine. That's the way the military was trained to operate. Until there was need for rapid fire, they were ordered to single load and hold the magazine in reserve.