It was ultimately deemed too complex and phased out by the 1980s (in favor of the M16 / M4 / M249 combo). A revolutionary modular design, it could be configured as a lighter assault rifle, light machine gun, lighter or heavier barrel, short commando, and other variants. It was put to use in very limited numbers in Vietnam by members of the United States Navy SEALs and several law enforcement agencies at the time. The real steel Stoner 63, also known as the XM22/E1, was an American modular weapons system designed by Eugene Stoner in the early 1960s. MK23 Best Airsoft Pistol Socom Navy Seals Spring Heavyweight W/Silencer & Extra. AIRSOFT GAS & CO2 SNIPER RIFLE MAGAZINES Spring airsoft guns give you an inside feel of the battle field, as.The Mk 23 enjoys continued service today with United States forces (including the Navy SEALs)as well as Indonesian, Malaysian and Polish special forces groups and special police units. AIRSOFT GRENADE LAUNCHER BB SHOWER SHELLS The 'Mk 23 Mod 0' was officially introduced in 1996 with deliveries forthcoming in May of that year.