guns

The M4 is the carbine variant of the AR-15 adopted by the United States Military, derived from the M16 assault rifle adopted by the United States. Manufacturers have changed over time in light of military contracts. The first M4s were made by Colt, and later also supplied by Fabrique Nationale.

Variants

M4

Introduced in 1994, this model features a collapsible stock, a carbine-length gas system, shorter handguards, and a 14.5 inch barrel with a notch to accommodate the M203 underbarrel mounted grenade launcher. The barrel assembly features M4 feed ramps; whereas the feed ramps in a rifle are angled at 45 degrees, the M4 feed ramps are longer and slightly steeper (52 degrees) to enhance reliability in the carbine system. The front sight block is also slightly taller ("F" marked). The FCG has three positions: SAFE, SEMI, and BURST. The earliest models featured an A2 upper receiver; flat-top models have replaced them.

M4A1

Same as the M4, except for the FCG, which has AUTO parts in place of the BURST FCG. The M4A1 also has the heavier SOCOM profile barrel, as opposed to the Government profile barrel used on the M4. Most M4A1 models were converted over from M4s. They were almost supplied entirely by Remington, but Colt protested the decision and won over 88 million USD to continue the contract, which is still being situated with the US government, with the goal of allowing more companies to provide M4A1s.[1] They are now also supplied by Fabrique Nationale.

CQBR

Main article: Close Quarters Battle Receiver

Replacement upper receiver for the M4A1 with 10.3 in (26 cm) barrel.

FN-15 Military Collector M4

A civilian marketed semi automatic M4A1 on offer by Fabrique Nationale, sporting changes such as the removal of the select fire capability and a 16 inch barrel to comply with US firearms laws. [2]

Trivia

External Links

References