[night-hunter]

Please also keep in mind that the ability to actually read hundredths and thousandths of an inch or tenths and hundredths of a millimeter are mid to late 20th century achievements. And that the variances in tolerance of the early machine tools caused "fit" problems. As an aside, not directly related to guns, when I first started working in 1978 in the Semiconductor field, the purity of the gases and most chemicals we were using were only 99.99% to 99.995% or so pure. By the late 1990s, the purity was 99.9999+% pure for the HPLC & Semiconductor Grades of gases and chemicals. Over the last 50 years or so, our technical ability to make accurate measurements has increased dramatically.