Colt Double
Three M-4 Carbine Uppers
Gas piston operation has great benefits. The weapon needs a lot less cleaning and lubrication, component life is greatly increased and the firing cycle is much less violent, enabling faster follow-up shots. Adams Arms are renowned for their AR gas piston conversions. The unit has no less than three settings to allow for normal use, use with a suppressor and manual operation for grenade firing etc.. The same system is also included on the Adams Arms upper. You can have an Adams Arms complete upper with a 16″ carbine barrel and M-4 handguard, but many users will want the 7 1/2″ pistol version which can be had with either D-ring quad rails or a version with a continuous top-rail.
PWS are unique in offering a long-stroke piston operating system for the AR. The Primary Weapon Systems piston upper is available with a 16″ M4 profile, 1:7 twist chrome-lined barrel fitted with PWS own combined compensator and flash hider to get your sights back on target even faster. PWS claim that their non-adjustable system does away with unneccessary adjustment and has been redesigned resulting in reduced carrier tilt, cam pin wear and carrier bounce. Their proprietary rail system enables each rail to be removed separately by the armorer for replacement or access to the barrel. Tangodown SCAR rail covers are provided to cover unused parts of the rails.
Colt carbine upper is regarded by some as the only ‘real’ M-4 upper. Colt holds the patent on the M-4 name. Colt uppers have the feed ramp cuts and are machined from 7075 aluminum which is hardcoat anodized. The USGI M-4 upper is US Armed Forces in all respects appart from the 16″ length of the step-cut, chrome-lined 1:7 twist barrel. The MarTech flip up backsight is US Army issue as is the double aluminum lined, heat resistant handguard. The Colt M-4 upper also comes in an Advanced Law Enforcement Carbine version which features a quad rail machined from the same billet as the receiver. This will not turn no matter how much torque you apply to the handguard. These are large pin uppers and the ALEC requires a proprietary barrel wrench to remove from the receiver.
Colt Double Eagle