DESIGN & DEVELOPMENT OF THE M-4 CARBINE
Despite the popularity of the older CAR-15 and it's
immediate successor, the Commando-both models lacked
one important thing. That being the ability
to hit at longer ranges, both models were more effective
as sub-machineguns that as true carbines or even rifles.
So in 1988 engineers at Colt began working on a new
carbine which they felt would be a viable alternative
to previous designs. The M-4 was to take advantage
of the lessons learned from previous attempts, for
one the weapons foregrip was engineered with a double
heat shield. This would keep the users hand
from being scorched by a a thin heat shield coming
from a hot barrel (see Figures 2-1 & 2-3).
An earlier design flaw noted in the CAR-15 was avoided
when a heavier barrel was used-this would allow the
weapon to be used "aggressively"
with a bayonet (see Figure 2-4). In many respects
the early designs were quite similar to the M-16A2
already in production, in fact 80% of the parts used
in the manufacturing of the M-4 are compatible with
the M-16A2 (Note The A2 Receiver On Figure 2-2). The
early models of the design (Model 720) were often
referred to as the M-16A2 Carbine as a result of the
resemblance between the two weapons. Strangely
enough there is a different version of the M-4, known
as the Model 723-instead of using a M-16A2 receiver
it is mounted with the receiver and rear sight from
the older M-16A1 (see Figure 3-2).
One problem with the earlier designs which Colt improved
up was using a slightly longer 14.50 inch barrel,
the result of this was to give the weapon more range
and also to allow it to use the M-203 grenade launcher.
The addition of the latter would be greatly appreciated
by units who were issued the weapon. Now they
had in effect a weapon which was more compact than
the M-16A2, just as accurate and capable of hitting
out to longer ranges and capable of giving them a
tactical edge with the M-203 and later PI-M203.
In 1994 the United States officially announced that
the M-4 Carbine Series would replace the venerable
M-3 Grease Gun in use, as well as selected M9 semiautomatic
pistols, and selected M-16A2 rifles. The typical
Colt M-4 Carbine is fitted with a three round burst
limiter, Colt however has produced a M-4A1 model which
is identical in most respects to the M-4 except it
is capable of firing full automatic.
Carbine Shown With Double Heat Shield Foregrip
M4 A2 Upper Receiver
M4 A2 Cutaway Of Double Heat Shield Foregrip
Colt M-4 "Heavy Barrel",
(Only Heavy From Gas Block Forward) And The
Proper Mounting Of M203 Sling Swivel And Step