If you were looking at the M24 (Army), then you were looking at the sight base for rear iron sights. The M24 is pretty unique looking, so there wouldn't be much out there to confuse it with, espicially anything that we (U.S.) are fielding. I've yet to see an M40A1/A3/A5 that had a side bolt release.
The M24 is made in house at Remington for the Army. The M40 series is made in Quantico by 2112s for the Marine Corps. Both use the 700 action, so there is your safety that you saw.
That is about as brief as I can get.
Played with both, have shot the M40A3, much prefer the M40 series.