Whats are the holes for!!

[Ron Wood]

A novel use for the hole no doubt, but it is intended, as Ed (Regul) said, to stake the follower button to the follower or to remove it for repair. The very early Luger magazines, the so-called "flat button" magazine, was made without this hole since the follower button was threaded and screwed into the follower. This early magazine is quite scarce and expensive.