I have a Colt Trooper marked “Trooper .357” SN 62,XXX. It is an “I” frame gun with internal firing pin, Colt target grips, silver medallion, wide hammer. Any references I have found seems to be for Trooper or a Colt .357 model - not Trooper .357. It seems nearly identical to a Colt OMM that I also own with the exception of caliber and front sight. Can anyone shed any light on this?