Those photos won't enlarge for me but it looks like a 4". The barrel measurment is taken from the front of the cylinder to the end of the tube, not from the front of the frame. What size barrel do you want? They made them in 2", 4", 6", 8", 10", 12" and 15". Do you have the barrel tool and .006" feeler blade for setting the cylinder gap?Here is a picture of the gun as well as the engraving. What add'l barrels do you suggest that I buy. This one measures a little over 3 in. Is it considered a 3 or 4?