PS Magazine - TB 43-PS-623
PS, The Preventative Maintenance Monthly
ISSUE 623
OCTOBER 2004
Both the M4 and M5
ARS use a rear clamp
with a screw and a for-
ward leaf spring to secure
the upper rail to the
M4/M4A1 or M16A4.
The clamp must straddle
the gas tube just forward
of either weapon's receiv-
er. The clamp should be
secured within the barrel
nut with the screw. The
forward leaf spring must
be inserted within the
hand guard cap.
The M5 ARS also has a
barrel stop assembly that
mounts within the hand
guard cap of the M16A4.
Without the assembly,
you can't mount the
M203A2 on the M16A4.
The M4 ARS doesn't need
the barrel stop assembly.
If the M4 or M5 is
mounted correctly, the
forward leaf spring is not
visible outside the hand-
guard cap and the rear
clamp is secured within
the barrel nut with the
socket head cap screw. If
the socket head cap self-
locking screw is removed
for any reason, it must be
replaced with a new one.
On the M5, also make sure the barrel stop assembly is mounted within the hand-
guard cap. The barrel stop must be installed in case the M203A2 must be transferred
between M16A4s. Replacing a barrel stop also requires replacing the socket head
cap screw.
PS 623
15
That's a
critical
question.
if the M4 adapter rail
system (ARS) is not
installed correctly on
the M4 carbine or the M5
ARS is not installed right
on the M16A4 rifle, the
ARS
won't
be secure.
That means any sight or
aiming device won't be
able to hold zero. And
you won't be able to
securely install the
M203A2 grenade launcher
on either weapon.
inspect your
M4/M4A1s,
M16A4s, and
M203A2s for
the following
ARS points…
Clamp
straddles
gas tube
M5 barrel stop
mounts within
handguard cap
Socket head screw must be replaced if it’s removed
Forward leaf spring
is inserted within
hand guard cap
Are
ARS
s
Mounted
Right?
M16-Series Rifle, M4/M4A1 Carbine,
M203A2 Grenade Launcher…
Cap
Clamp
Cap
Stop
623.14-15(C)
8/28/04
11:57 AM
Page 1
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