If you have some specific examples of what you're talking about, that would help. However, vaguely clockwork-like devices in firearms did exist, and many cap-and-ball revolvers during the second half of the 1800s did rely on mechanisms in the gun to automatically rotate the cylinders.
In early firearms, the most clockwork-like device one would expect to see is a wheellock. Wheel locks were a firing mechanism that worked similar to the sparking wheels we see on many lighters today - a wheel would be wound under tension, loose powder would be placed around it in the flash pan, and a piece of iron pyrite held on an arm would be lowered to contact the wheel. On pulling the trigger, the wheel would be released to spin and produce sparks as it scraped the iron pyrite. While reliable compared to the matchlock system that was in wider use contemporary with it, Wheel locks were more expensive to produce due to their more complicated mechanism and more time-consuming to reload, as the user had to wind the wheel as part of the loading process. The system would fall out of favor in Europe once the significantly more simple flintlock system became prevalent.
In terms of mechanics, however, revolvers are probably more what you're looking for. Revolvers, at least once they began to appear in the form that we're used to today, had a cylinder rotated by the force provided by the user's pulling of the trigger. Some went a step further, using that same trigger pull to also pull the hammer back before releasing it - a process known as Double Action. For all the mechanical complexity of these, however, non-cartridge-firing revolvers were very slow to reload once the cylinder was empty. Because the cylinder itself was acting as a cartridge (or chamber), reloading a revolver was a process much like reloading a muzzle-loader multiple times - a cap had to be placed in the back of each chamber, powder was put in the front, and a ball or bullet would be placed at the front to seal it.
Beyond revolvers, however, I'm not aware of any mechanically-operated system that would be a "true" repeater prior to the development of cartridges.