Threaded Mandrel and nose pieces for the DMSeeleysTools Rivet Nut gun in 3 different inch sizes. The replacement Mandrels are $29.95 a piece and are of high Carbon Steel. The thread end of the nose piece is grooved to prevent slipping. Using oil on the Mandrels threads will help to extend thread life.
The Pneumatic Quick Change Rivet Nut Gun Puller hand tool from DMSeeleysTools USA comes with inch nose piece Mandrels ( 1/4", 5-16", & 3/8") or 1/4-20, 5/16-18, 3/8-16 and is for Aluminum & Steel Rivet Nuts.
Note DMSeeleysTools also sells a Metric Versions.