As a starting point, having the first two or three digits after the C would help, as all combat masters made with the newer Caspian frame had a C prefix. If it is a blue gun, there would not be an "R" in the serial number. It would be Cxxxxx rather han CRxxx. Also, if the slide is polished and there is a "Mark IV" engraved on the left side under "Detonics .45" then it is a Mark IV. Usually the Mark IV had the "Combat Selector" sight (two set screws, replacable leaves), while the Mark I used the regular Combat Master sight (one set screw). Otherwise, it is a Mark I. Many guns listed as Mark IVs are really Mark Is. The Serial and Model will help get some idea when it was made, but even that is a little uncertain. See Conley's Detonics Info on the Detonics Collectors site at Yahoo.com .

http://groups.yahoo.com/group/DetonicsCollectors/files/

As far as testing it, if you are new to the gun (and guns), I suggest you take the gun with you to one of the local gun ranges that rent guns (Wades, Sam's the Marksman) and first get a little practice and instruction with the standard 1911 style pistol. When you are comfortable shooting that, the transition to the smaller Detonics and its variations is pretty easy. If you let your pinky finger hang below the grip you probably will find your accuracy will be better. Maybe you can get your coworker's father in law to go with you and help you get started with it.