Abstract: Removable front sight for the barrel of a firearm has an upper blade portion and a lower keel portion. The keel portion is undercut and adapted to fit into an upwardly opening recess provided in the upper surface of the gun barrel and adjacent the front end thereof. A cylindrical hole extends longitudinally from the muzzle end of the barrel, communicates with the recess, and terminates rearwardly thereof to provide a housing for a combination spring and detent disposed therein. The detent is releasably urged forwardly by the spring to engage the inner end of the keel. A cross-pin is fitted across the recess to engage the forward end of the keel and to prevent removal of the spring and detent from the cylindrical hole. The spring is rearwadly compressible sufficiently to enable insertion and removal of the keel from the recess from between the detent and cross-pin.