Starting with T6 temper 7075 aluminum (an aluminum alloy with strength comparable to many steels), our AAM4 forged upper receivers are then forced under great pressure to produce high-strength Aircraft grade forgings. After passing through a number of quality control checks, we precisely CNC machine these high strength forgings into our “A4” variation of upper receivers. After passing through another series of quality control checks – these AAM4 upper receivers are then hardcoat anodized per our mil-spec+ standards. Again the Upper Receivers pass through quality control screenings before being laser engraved and assembled with dust cover and forward assist before – you guessed it – a final round of quality control. Airborne Arms is a Combat Veteran owned small business and all of these manufacturing and inspection steps take place right here in the USA.
Airborne Arms AAM4 Forged Upper Receiver Assemblies
- Laser Engraved American Paratrooper and AAM4 logos (not shown in photos)
- Precision CNC Machined from 7075 T6 Aluminum Forging.
- Hard Coat Anodizing for added strength and durability.
- M4 Feed Ramps
- Laser Engraved “T” Markings
- Forward Assist assembly (installed)
- Dust Cover assembly (installed)
- M4 Feedramps
- .250 takedown pin holes
- Lazer engraved T-marks
- Machined and assembled right here in Minnesota, USA
- One AAM4 Stripped Upper Receiver in Anodized Black
- One Forward Assist Assembly (Installed)
- One Dust Cover Assembly (Installed)
History of the “A4” Style upper receiver:
A1 Upper Receiver
The original upper receiver introduced for the platform, the “A1” was developed in the 60’s and installed on the M-16 A1 rifles used by soldiers in the Vietnam War. The “A1” designs distinguishing features included:
- A Forward Assist
- A Fixed Carrying Handle
- A flip up rear sight that adjusted for wind-age (but not elevation)
- Rear sight is equiped with both short and long range apertures
A2 Upper Receiver
In the early 1980’s the “A2” upper receiver was introduced as an upgrade to the “A1”. The A2 design improvements included:
- A more advanced rear sight that is adjustable for both elevation as well as windage.
A3 Upper Receiver
The “A3” upper receiver was introduced to allow for a variety of optics to be used without drastically changing the cheek weld used to operate them. The “A3” upper receiver design features the following design improvements:
- A flat top rail (either picatinny or weaver depending on the model) to allow for a variety of optics and accessories to be mounted.
- Rifle cuts in the feed ramps.
- A few “A3” models are available in a “high rise” configuration that extends the base upwards providing a higher scope positioning.
A4 Upper Receiver
The “A4” model upper receiver design (of which the AAM4 A4 forged upper receiver is based) improves upon the “A3” flat top design with the main improvement being:
- The “A4” model upper receiver employs M4-style feed ramp cuts. These feed ramps improved reliability and opened even more caliber versatility on the platform. The “M4” style feed ramps quickly became the adopted standard across the industry and they remain the standard to this day.