Operator's Manual

14
15
15. Alternate usage of barrel assemblies to minimize wear
(if available).
16. To avoid damage to equipment, DO NOT use dry cleaning
solvent on plastic components.
17. DO NOT use abrasives to clean the bore, piston, gas cylinder, or
gas block.
18. DO NOT lubricate chrome-plated areas of piston, gas cylinder,
or gas block.
19. BE SURE TO CLEAR RIFLE AND ALLOW IT TO COOL BEFORE
DISASSEMBLY, CLEANING, INSPECTING, TRANSPORTING
OR STORING.
20. Do not allow ammunition to hit any hard surface or it may fire.
Dispose of live rounds appropriately.
21. If ammunition is wet or dirty, wipe it off with a dry rag prior to
use. Do not lubricate ammunition. Dust and other abrasives
that collect on oily ammunition are damaging to operating
parts of the rifle. Lubricated cartridges produce excessive
chamber pressure.
22. ENSURE THE SAFETY IS IN THE FIRE POSITION WHEN COCKING
THE SLIDE HAMMER. COCKING THE SLIDE HAMMER WITH THE
SAFETY IN THE SAFE POSTION MAY CAUSE DAMAGE TO THE
SEAR OR SLIDE HAMMER. ONCE THE SLIDE HAMMER IS
COCKED, IMMEDIATLY PLACE THE SAFTY SELECTOR IN THE SAFE
POSTION AS EXPLAINED IN SECTIONS 10 AND 11.
5. GENERAL FIREARMS SAFETY INFORMATION
1. Treat every firearm as if it is loaded, even if you have verified it
is unloaded.
2. Keep the firearm pointed in a safe direction at all times.
3. Keep your finger off the trigger until you are ready to fire.
4. When possible, keep the safety selector in the SAFE position
until you are ready to fire.
5. Only load the firearm when you are ready to fire and firing is
imminent.
6. DESCRIPTION AND OPERATION
6.1. Description
The FN M249S
™
is a semi-automatic only version of the legendary
M-249 Squad Automatic Weapon(SAW). The FN M249S
™
is a piston-
driven, gas operated, air cooled, belt or magazine fed, semi-
automatic rifle that fires from a closed rotary bolt. It is based on
proven designs successfully used for decades in rigorous military
service and benefits from advanced manufacturing techniques to
deliver extreme reliability and durability expected by the most
demanding operators.
The FN M249S
™
features the ability to change barrels quickly to
extend barrel life when firing long sustained strings of fire by
keeping the barrel from overheating. Also unique to the FN M249S
™
is the ability to feed from either a disintegrating link belt out of a
200 round box/ammunition pack or from M-16 style GI pattern
magazines.
When properly used and maintained, the FN M249S
™
will deliver
years of dependable and enjoyable service.
This information applies to basic operation of the FN M249S
™
rifle,
regardless of the specific model you may have purchased.
Instructions for option accessories available after initial purchase
or included on some models are covered here. Where applicable,
these differences are explained or are included in a separate
addendum included with your FN M249S
™
rifle.
6.2 Operation
When the trigger is pulled, the slide hammer is released, striking
the firing pin resulting in the rifle firing the cartridge in the
chamber. Gas from the fired cartridge travels down the barrel with
some diverted into the gas block below the front sight assembly
and onto the piston face. This gas imparts some of its energy to the
piston and carrier assembly, forcing it to move to the rear. During
the rearward movement of the piston, carrier and bolt, the bolt
unlocks from the barrel extension and the empty case is extracted
from the chamber. As the bolt clears the ejection port, the empty
casing is ejected out of the ejection port. If fed from the belt, a
single link will be ejected from the link ejection port. During this
time, the slide hammer is re-cocked by the carrier assembly. If the
rifle is fed from the belt, the feed tray cover assembly advances a
new cartridge into the loading position of the feed tray. The bolt
and carrier assembly begin to travel forward under the spring
tension of the drive spring and strips another cartridge from the
feed tray or magazine and loads it into the chamber, ready to be
fired. If there is no more ammunition present, the bolt will close on
an empty chamber.
With cartridges in the magazine or on the feed tray and in the
chamber, and the safety selector in the FIRE position, the rifle will
fire a single round with each successive pull of the trigger until the
magazine, feed tray and chamber are empty. When the last round is
fired, the bolt will not lock to the rear.
7. NOMENCLATURE
In normal firearm terminology the position and movement of the
part are described as they occur with the firearm horizontal and in
the normal firing position, i.e., the muzzle is forward or in the front;
the buttstock is rearward or to the rear; the trigger is downward or
underneath; and the sights are upward or on top. For general part
nomenclature, refer to Figures 1 and 2.
8. SERIAL NUMBER
Serial number location marked on right rear side of receiver. See
Figure 3. Record this serial
number at the front of this
Operator’s Manual and in
another secure location for
future reference.
9. INITIAL CLEANING
Various exposed metal parts
of this rifle have been coated
FIGURE 3