Abstract: A range of staple sizes, including different leg lengths as well as different leg spacings, is enabled to be handled by a single gun. The smallest leg spacing staples of the range are guided by a pair of spaced parallel inner rails of a magazine into driving position, the staples of greatest leg spacing straddle said rails and are guided by parallel outer walls of the magazine, and intermediate leg spacing staples are loosely guided by the inner rails and outer walls. A desirable alternative construction has these outer walls provided with centralizing leaf spring guides yieldable widthwise. No limitation on the leg lengths is imposed, and a spring-urged pusher in the magazine has its leading end provided with portions projecting inwardly widthwise thereof to insure advance of the narrowest as well as the widest staples.