Well, I will say it: "heck no. you can't hurt on old, well used gun by putting a few light dove loads through it." But some old guns can be damaged or even blown by use of modern smokeless powder loads, even light loads.
I do suggest having the guns checked out by a knowledgeable gunsmith, not only for safety but also for the right length shells. Also make sure none have Damascus ("twist") barrels. The Model 12's should be OK but the Colt is black powder era and may be unsafe to shoot, even with black powder.