I joined the Army in 1975 and didn't see a Beretta M9 until I qualified with one during Desert Storm in 1990. Prior to that, soldiers were issued 1911's or .38 revolvers. I saw lots of 1911's and .38 revolvers, from a variety of manufacturers.
I doubt that his platoon had a logo. Regiments have crests. However, some units informally adopt symbols.