The only things that I see stamped on the barrel is Chas Osborne. I have not found much about the manufacture or who this was. The cylinder is numbered at each cylinder with, I think a proof mark, at each partition between the nipples. There is a small cavity in the grip about an inch deep. The tab on the left side behind the cylinder will hold the hammer back to allow for cylinder rotation and releases when the trigger is pulled. It is also a double action only operation. I did not measure but it seems to look like a .40 something cal. maybe a .44. Thanks for any help and sorry for any quality issues with the pics.