a. Remove the magazine from the carbine, if there is one present.
b. Cock the carbine.
c. Turn the selector to SAFE.
d. Lock the bolt open.
(1) Pull the charging handle rearward.
(2) Press the bottom of the bolt catch.
(3) Allow the bolt to move forward until it engages the bolt catch.
(4) Return the charging handle to the forward position.
(5) Ensure the selector is on SAFE.
e. Check the receiver and chamber to ensure they do not contain ammunition.
2. Disassemble the carbine.
a. Remove the sling.
b. Remove the handguards if you can see dirt or corrosion through the vent holes. Handguards are interchangeable because they are identical.
c. Push the takedown pin as far as it will go and pivot the upper receiver from the lower receiver.
d. Push the receiver pivot pin.
e. Separate the upper and lower receivers.
f. Pull back the charging handle.
g. Remove the bolt carrier and bolt.
h. Remove the charging handle.
i. Remove carrying handle assembly. Loosen the round nuts on the left side of the carrying handle approximately four turns. Loosen the clamping bar from the left side of the upper receiver and lift off the carrying handle.
j. Remove the firing pin retaining pin.
k. Put the bolt assembly in the locked position by pushing in the bolt.
l. Remove the firing pin by allowing it to drop out of the rear of the bolt carrier into your hand.
m. Remove the bolt cam pin by turning it one-quarter turn and lifting it out.
n. Pull the bolt assembly from the carrier.
o. Press the rear of the extractor pin to check spring function. Report any weak springs to unit armorer for replacement.
p. Remove the extractor pin by pushing it out with the firing pin (use care not to damage the firing pin).
q. Lift out the extractor and spring, taking care that the spring does not separate from the extractor.
r. Release the buffer by pressing the buffer and depressing the retainer.
s. Remove the buffer and action spring separating the buffer from the spring.
t. Extend the buttstock assembly to full open. The M4/M4A1 has a four-position buttstock: closed, 1/2 open, 3/4 open, and full open.
u. Grasp the lock lever in the area of the retaining nut, pull downward, and slide the buttstock to the rear to separate the buttstock assembly from the lower receiver extension.
3. Clean the carbine.
a. Upper receiver group.
(1) Use small-arms swabs, CLP, and bore brush to clean bore.
(2) Use rags, cleaning brush, and CLP to remove powder fouling, corrosion, dirt, and rust from other areas.
(3) Clean bolt lugs with CLP and chamber brush.
(4) Use CLP and bore brush to clean barrel locking lugs and gas tube.
b. Lower receiver group.
(1) Remove powder fouling, corrosion, and dirt with rags, cleaning brush, and CLP.
(2) Clean buffer tube and buttstock tube with rag attached to holder.
(3) Clean buffer action spring and inside lower receiver extension with brush and rags.
c. Bolt carrier group.
(1) Clean outer and inner surfaces of bolt carrier with rags and CLP.
(2) Clean carrier key (use worn bore brush).
(3) Clean firing pin recess and firing pin with brush and CLP.
(4) Clean firing pin hole with pipe cleaner and CLP.
(5) Clean carbon deposits and dirt from locking lugs with cleaning brush and CLP.
(6) Clean areas behind bolt ring and under lip of extractor with brush and CLP.
4. Inspect carbine for serviceability.
a. Upper receiver group.
(1) Check for free movement of the forward assist assembly.
(2) Check for broken or damaged ejection port cover.
(3) Check rear sight windage and elevation knob for damage and looseness.
(4) Check carrying handle assembly for missing or damaged parts and ensure the handle assembly will mount to the upper receiver.
(5) Check front sight assembly for damage.
(6) Inspect bore and chamber for pitting or obstructions.
(7) Inspect bolt lugs for cracks and burrs.
(8) Check for free movement of slip ring.
(9) Check the compensator for proper alignment.…