***and you have your 7-rounders.***
Place the magazine in the pistol, load a round in the chamber. You now have a magazine with six rounds in it.
Drop the magazine and replace the one round. Now you have one in the chamber, and seven in the magazine.
If you have to shoot, count your rounds, after seven is fired, you will still have one in the chamber to take care of anyone rushing you as you change magazines.
Yep. And with a worked-in magshift, you have a full mag before the empty hits the ground.