Operator's Manual

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With the handguard, heat shield and buttstock assemblies
removed from the receiver, use an all purpose brush and
military-grade cleaner/lubricant to remove debris and excess
lubricant from their exteriors.
Warm soapy water and an all purpose brush can be used to
clean the polymer components if they become excessively dirty.
All to air dry or wipe dry with a clean cloth. Compressed air
can be used to assist in
cleaning the interior
locations. Dry, clean cloths
should be used to wipe off
any excess lubricants and
debris. See Figure 84.
When clean, apply a thin
film of military-grade
cleaner/lubricant to all
exposed metal parts.
25.9 Magazine/Ammunition Pack/box
Cleaning the magazine
FN America does not recommend disassembling the
magazine. Frequently inspect to determine the need for
cleaning as lubricant and dirt will gradually collect in the
magazine.
Clean the magazine by spraying it with a polymer-safe
aerosol gun cleaner that will not adversely affect the follower
or corrode the metal components. Spray the magazine with
this solvent, both inside and out to loosen debris.
Drain the solvent and residue from inside the magazine.
Used compressed air to dry the magazine or allow it to air dry
and lightly oil the exterior. Do not apply lubricant to the
interior of the magazine.
Cleaning the plastic ammunition box
Disassemble the plastic box by removing its cover.
Use warm soapy water and an all purpose brush to clean
away debris, lubricants and fouling.
Allow to air dry or dry with clean cloths.
Reassemble by installing the cover. Do not lubricate the
plastic ammunition pack.
25.10 Lubrication in Adverse Conditions
In most adverse conditions, increased and more frequent
maintenance will ensure your FN M249S
™
continues to operate
effectively and safely. Once you have left such an environment,
perform a more detailed cleaning of your FN M249S
™
. Follow the
below guidelines for specific conditions:
1.Dry and Dusty Conditions
• More frequent cleaning may be required where dust and
blowing sand can enter the rifle. Use a brush and
compressed air to remove.
• Keep dust cover closed when possible to limit the debris
that can enter the receiver.
• Keep magazines, ammunition packs and ammunition
protected and inspect them frequently for sand and dust.
Do not lubricate magazines, ammunition packs or
ammunition, including links.
• Corrosion will be less likely in dry conditions, so less
protectant is required on external parts. These protectants
will only attract more dust and sand.
• Use only minimal lubricant on internal parts.
2. Hot and Humid Conditions
• Increased inspection of all steel parts for corrosion and
rust, including under the handguards. Apply military-
grade cleaner/lubricant as needed to prevent rust from
forming.
• Corrosion will be more likely in a hot and humid
environment, so additional protectant may be required on
external parts. Wipe them frequently with a cloth to
remove fingerprints and moisture. Reapply military-grade
cleaner/lubricant as needed.
• Keep magazines, ammunition packs and ammunition
protected and dry. Inspect frequently for the presence of
moisture. Avoid placing ammunition in direct sunlight.
• Normal lubrication of internal parts will suffice.
3. Extreme Cold Conditions
• Keep the dust cover closed when possible to limit any
frozen or freezing precipitation from entering the rifle.
• Keep magazines, ammunition packs and ammunition
protected and dry. Inspect frequently for the formation of
ice.
• Avoid taking the rifle from warm, moist indoor
environments to the cold outside environment and back
as condensation (moisture) will form and freeze on and
inside the rifle.
• Wipe the exterior of the rifle frequently to remove any
moisture and reapply protectant to exposed steel parts.
• Avoid excess liquid lubrication on internal parts as these
lubricants may stiffen at lower temperatures and cause
malfunctions. Use minimal lubrication.
• Use a lubricant specifically formulated for low
temperatures.
26. ASSEMBLY
1. Install Forearm / Handguard Assembly
To install the forearm / handguard, ensure the retaining pin is
to the left as explained in Section 24.14.
FIGURE 84