Arik, a reader from Israel, emailed me this photo of a XEM16E1 rifle he was issued. He wrote …
I was issued this rifle for a month, belonged to the Nahal infantry battalion and was still in full active service and firing rounds.
The XEM16E1 was produced approximately from 1963 until 1967 when the US Army adopted an upgraded version, the M16A1. The means that the above rifle must be at least 48 years old.
The XEM16E1 differed from the M16 in that it has a forward assist, something Eugene Stoner (and apparently the US Air Force) believed to be superfluous. Whether or not an AR-15 needs a forward assist is still hotly debated today.