Some have removable base pads, which you can slip off by pushing from rear to front.
On the welded mags, push the follower into the mag, use a pin or paperclip to trap the spring, and manipulate the follower out of the top of the mag. Pull the pin and remove the mag spring from the top of the mag. Re-assemble in reverse order.
Yep, when you insert something small enough to go through one of the holes in the mag to hold the spring down, the follower will just fall out.. Be sure to look at how the spring is when you take it out so you wont put it in backwards.. -Gilmore