You don't have to take the mag. tube off for that. The far end of the tube typically has a C-style cup pressed in, with the spring under that. You can pry it out carefully as long as you know that the magazine spring will be under lots of force behind it. Also realize there is probably a magazine plug inside there as well, limiting the magazine to only two shots (hunting regulations). Remove the plug and you can load four shots, + one in the chamber.