Only M16, M60, M203, M148, 1911/A1 for the US Army troops in Germany unless it was privately obtained and kept out of site. The sidearms were for officers and Military Police/OSI and such, not common troops. The Germans had strict rules about such.
"Held in reserve" was more likely strictly Cold War support. The US Army had tons of tanks and a few dozen Pershings pointed at the USSR then and the US Army stood guard duty along borders and around compounds.
Above is based on the opinion of a 20 year Small Arms Marksmanship and Training Unit USAF instructor with more than 30 years in competitive shooting sports. Your mileage may vary.