The M1911 & M1911A1 pistols were purchased by the US military from 1911 until the end of WWII. These were the standard issue pistol of the US military until the M9 was adopted in 1985. It took well into the 90's for the M9 to completely replace the M1911. That means that the newest M1911A1s were made in 1945. That means that the newest guns were 40-50ish years old and were still in service. I'm sure that many of them were quite a bit older than that.