A follower for a firearm magazine includes a base part, a guide, a cartridge engaging part, and a slide stop actuating structure. The base part provides a lower surface against which the magazine spring acts, and the guide provides a guide surface extending transverse to a base plane defined by the base part. The cartridge engaging part provides a spring action within the follower itself to augment the force of the magazine spring. The slide stop actuating structure is located at a front end of the base part and provides an inclined engagement surface that extends upwardly from the front end of the base part to a front edge of the follower. This upwardly angled surface forms an engagement surface to reliably engage a slide stop lug of a firearm to actuate the firearm's slide stop mechanism when the magazine is empty.