I know the font for the right side of the barrel with the Colt's logo changed over the years but, although both my '67 Python with the 6" barrel and my '61 Pyton with the 4" barrel have the same older font, the font on the '61 is smaller. There are other differences, on the '61 it's CO. whereas on the '67 it's Co. with a line under the o. , on the '61 it's CT.USA. on the '67 it's CT. USA. Were they always different back then based on barrel length? Looking back even farther on this sight a guy posts a pic of a 6" '57 Python with almost identical font to my '67 and with Co. instead of CO. Just curious. Thanks.