Factory Ruger Mark 1 2 3 IV 4 Mainspring also fits 22/45 MK 2 3 IV *B18

Description Factory Ruger Mark 1 2 3 IV 4 Mainspring also fits 22/45 MK 2 3 IV Fits Mark Series 1, 2, 3 and 4 Pistols Standard and 22/45 Replacing a worn out mainspring can help with light strikes. With Marks 1-3, detent balls commonly get launched into the fourth dimension when replacing these, so it’s a good idea to make sure you still have it.