M1921/1928/1928A1 Submachine Gun
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M1921/1928/1928A1 Submachine Gun

The M1928A1 submachine gun is one of the most famous, most recognized guns in the world. First designed and made in an era when cheap labor enabled lavish expenditures of time and materials, the M1928A1 was an over-engineered, bulky, heavy gun. The M1928A1 answered a question that had not been asked yet: What kind of gun is needed for mobile troops on a rapidly changing battlefield? For mounted troops? For urban warfare? For paratroops? When World War II came along and "asked" these questions the M1928A1 was the only answer. Auto-Ordnance had still not sold all of the original production run of 1921. It was a beautiful gun. It was reliable. It did not wear out. And it fired the biggest pistol cartridge anyone had - the .45 CAP. But the realities of war overcame this wonderful gun. The M1928A1 took too long to make, and was too expensive to make. Production was simplified, and finally in mid-war the production of the M1928A1 ceased in favor of the M3 Grease gun. To say that the pendulum swung the other way would be an understatement. Later advancements in gun and ammunition design eliminated the need for a submachine gun. The M1928A1 remains one of the unique American icons. In its glory days of W.W.II it provided un-equaled close range firepower to American and Allied troops. It served on through Korea and  Vietnam. Nobody is sorry they carried one. This gun is hugely popular due to its use in Korea and Vietnam, frequent use in gangster and war movies, and due to the
"revival" of interest in World War II.

The M1921 is the original production version as made by Colt Firearms in 1921. These guns are of the highest quality, fit, and finish, being made like high grade sporting firearms, not military firearms. These guns feature finely machined and fitted parts, beautiful wood, and high polish Colt royal blue finish. Standard characteristics are finned barrels, some with compensators, knurled lightweight actuators, Lyman Model 55B adjustable rear sights, push button detachable butt stocks, vertical fore grips and checkered fire control levers.

The M1928s are the same as M1921's but with heavy actuators and smaller less powerful recoil springs to reduce the rate of fire. The earliest of these were converted M1921s re-stamped 1928 (hence the terminology "overstamp").

The M1928A1 is the military pattern ordered by the government in 1928. The M1928A1 has a standard "military" blue finish (blue-black finish, not highly polished like the Colts) a heavy actuator, and a horizontal fore grip. This model was made in great quantities during early W.W.II. Towards the end of its production shortcuts were taken to reduce production time, the ultimate shortcut being the M1 models. Later M1928A1's may have smooth barrels, no compensators, fixed "L" shaped rear sights, and no checkering or knurling on actuators and fire control levers.

The receiver we make will accept parts from M1921, M1928 and M1928A1 sub machine guns.

Features of Phila. Ordnance 80% Machined
M1921/M1928/M1928A1 Receivers
  • Machined from 4130 aircraft quality steel (higher quality and strength than originally used.
  • 100% machined exterior, all contours and surfaces are fully machined.
  • Accepts original M1921, M1928, or M1928A1 parts.
  • Threaded for barrel, slotted for grip mount.
  • Fully machined ejection port, magazine well, and feed ramp.
  • Trigger frame rails machined
  • Ejector hole drilled and threaded
  • Buffer pilot and frame latch hole drilled and reamed.
  • Actuator slot machined
  • Drum mounting slots machined
  • Rear sight mounting holes spotted
  • Drawings included
  • Price $295.00
  • add $30.00 for Military Blue or $20.00 for Parkerized
  • Original type engraving (correct size and font) $50.00
  • For engraving block of Patent Numbers add $30.00
  • add freight and insurance

Notes on M1921, M1928, M9128A1 80% receiver:

It is not legal to finish this receiver into a machine gun without the proper license. You can make a non-firearm (DEWAT, blank gun). You do not need to be a licensed manufacturer to make a legal type (semi-auto, single shot) firearm for your own use as long as it is not for resale. Many people use this receiver to make a semi-auto using existing spare parts as this receiver, being made from 4130 aircraft quality steel is much stronger and tougher than the semi-auto receivers available elsewhere. Contact ATF for guidelines on the manufacture of legal semi-auto rifles or blank fining devices.