My question is, if I buy a .22lr cylinder for it can I just switch out the magnum cylinder?
Yes, it's likely that it originally came with both cylnders. Many or these models came with them. Now it possible that your didn't. Might want to do some digging or asking. ....
I am not currentl on how colt responds to these models. I do know that Numrich Arms has listed some in the past. Kindly let us know how you make out as I have a personal interest. ...
Be Safe !!!