Junkman is mostly right: BUT, you need to have the same MANUFACTURER for the two grip styles & frame. e.g. an ASM '60 Army grip won't go onto a '51 Navy Pietta frame. However I have a gun that I swapped off the Pietta navy grips and traded a fellow for army grips and all is well. Original Colts could be ordered with either style grips from the factory so you are not alone in wanting the right grip on the right gun.