Greetings. My first weapon ever was a .38 Spcl. 2" barrel, square butt, 6 round capacity (bought 1960) . I've since had 2 model 10 Military and Police. Today I was given 2 S&W beauties: both .38 Spcl. 1 7/8" Barrel, 5 round capacity, round butt, concealed hammer; one has Airweight stamped on the barrel. How can I find out when they were made?