Ordnance Notes -- by Bob Stoner GMCM (SW) Ret.
Stoner 63 and 63A 5.56mm Machinegun
The Stoner 63 and 63A 5.56mm machinegun has developed a somewhat mythic status as part of the Vietnam-era SEAL armory. Dr. Eugene Stoner's idea was for a modular, gas-operated, selective firearm that could be made into a rifle, a carbine, a belt-fed machine gun (right or left feed), a squad automatic weapon with top feed (similar to the British BREN gun), a belt-fed medium machine gun, and a solenoid-fired fixed machine gun for vehicle use.
The receiver module was the heart of the package. It had a spring-loaded ejection port covers that opened to allow the bolt to eject the fired case to either the left or right depending on the configuration. Lugs attached to the receiver were used to attach the sights, lower receiver group, magazine wells, or top covers and belt feed mechanisms.
Depending on the configuration of the gun, the gas cylinder could be either above or below the barrel. All Stoners used quick-change barrels in various lengths and sizes. All Stoners used the multiple lugged rotating bolt assembly pioneered by the AR-10 and AR-15 rifles.
The Stoner 63 and 63A was manufactured by Cadillac Gage Corporation. (Cadillac Gage also manufactured the V-100 and V-150 four wheeled armored cars used by American Military Police and Vietnamese forces during the Viet Nam War.) The Stoner Weapon System evolved through combat use in Vietnam. The first guns were of the Stoner 63 style and approximately 2,400 were made from 1963 through 1966. An additional 850 Stoner 63A guns were made between 1966 and 1969, and approximately 100 Mk 23 Mod 0 Stoners were made for the Navy’s SEALs in 1969.
The Army had two different versions made up for evaluation by its special forces units as the XM207 and XM207E1 in early 1970, but no production figures are available for those pieces. Stoner production ceased altogether by the end of 1971. Total production for U.S. and foreign users would probably in the 3,500 to 4,000 unit range.
Most SEAL Stoners were of the belt-fed, light machinegun (LMG) variety such as the Stoner 63A Commando (which had a shortened barrel). The gun used either a 150-round snail drum that attached beneath the gun and fed from the left or a 100-round plastic box that mounted sideways beneath the gun and fed from the right. Experiments were tried with larger or smaller drums and boxes for the "correct mix" of firepower, portability, and reliability.
One of the problems with the snail drum magazine, left hand feed guns was spin back. That is, rounds ejected into the feed chute of the snail drum and sometimes bounced back into the ejection port to jam the gun (links were ejected to the right). On guns with the box magazine, right hand-feed eliminated spin back because both links and brass were ejected to the left without any obstructions.
A clip-on bipod was available for the LMG, but SEAL operators usually did not use it in the field. SEAL operators who used Stoners treated them with the care one lavishes on thoroughbred racing cars such as a Ferrari. Cleaning, lubrication, and inspections of parts were rigorously applied to the Stoners and they responded with awesome firepower.
If there was any criticism of the Stoner, it was that it had a lot of small parts and required a lot of care in order to perform. Later operators of the XM207 series had malfunctions because they did not maintain their Stoners with the zeal the SEALs did with theirs. The pioneering ground broken by the Stoner machine gun lives on today in the forms of the Fabrique Nationale M249 belt and magazine-fed squad automatic weapon (SAW) and its Mk 46 Mod 0 descendant.
63 and 63A (Mk 23 Mod 0) SPECIFICATIONS:
© 2005 Bob Stoner R4