Hi, Gary -

Thanks for the quick reply. The cylinder has only five chambers. If as I suspect this isn't my grandfather's but GREAT grandfather's, then your estimates put it at about the right time in terms of years. The break on the top does not seem to work but might if properly oiled. The cylinder does rotate when the hammer is cocked, but it takes a great deal of effort & I suspect is obviously due to age, some rust, lack of care, need for oiling, etc.