Now wait a minute, most gunsmiths will refuse to tune a gun without the maagzine for a couple of reasons...
1) Bleeding hard to load, even with a single shot tray, which would also not have been supplied.
2) You cannot check for accuracy without the magazine, as if it was misaligning and clipping the pellets they would be all over the show.
So either you tried to improve a gun you really could not, or a magazine was supplied.