From what I can tell, he almost always has a revolver of some sort on him but he definitely hesitates to use it. In Raiders he uses a S&W M1917 and a S&W Mk II Hand Ejector, neither of which are in the game. I figured the 610 was a good substitute, but maybe the 619 would work a little better. I was also considering having the archaeologist start with the gun but no ammo to make it more Jones-like.