Warning Handling

Never carry the rifle loaded with the safety lever in the "F" (FIRE) position. If dropped or struck with the safety off ("F"), the rifle may fire. Such a discharge can occur with or without the trigger being directly struck or touched. Never rest a loaded rifle against any object (wall, tree, fence, vehicle, etc.) because there is always the possibility that the rifle will be jarred or slide from its position and fall with sufficient force to discharge. Keep the safety lever on "S" (SAFE) unless actually firing.

Sig 556 Charging Handle


3.2. Loading The Weapon

Insert The Magazine Rifle

1. Ensure the safety lever is in the "S" (SAFE) position;

2. Insert the magazine and check that it is properly seated;

3. Bolt forward: Pull the charging handle back fully and release; or

4. Bolt locked open: Depress bolt catch fully to release bolt.


DO NOT LOAD A RIFLE WITH A HOT CHAMBER BECAUSE A ROUND MAY "COOK" OFF (i.e., a round may detonate (fire) unexpectedly just because it is exposed to the heat of the rifle's chamber).

3.3. Loading The Magazine

1. Ensure the magazine is the proper type and caliber for the rifle;

2. Hold the magazine vertically;

3. Place a round between the feed lips and press down - ensure the bullet is facing the front of the magazine; and

4. Place the next round on top of the previous round and repeat until the desired number of rounds are loaded.

Sig 556 Bolt Release Catch

3.4. Changing The Magazine

1. Ensure the safety lever is in the "S" (SAFE) position;

2. Remove the magazine by depressing the magazine catch;

3. Insert loaded magazine and check that it is properly seated.

3.5. Reloading (Rifle Empty, Bolt Locked Open)

1. Ensure the safety lever is in the "S" (SAFE) position;

2. Remove the empty magazine by depressing the magazine catch;

3. Insert a loaded magazine and check that it is properly seated;

4. Release the bolt:

a. Depress the bolt catch fully; or b. Pull the charging handle back slightly and release.

Charging handle

Charging handle

Sig 556 Bolt Release Catch

Always make sure the muzzle is pointed in a safe direction!

Never attempt to load or unload any firearm inside a vehicle, building, or other confined space (except a properly constructed shooting range). Enclosed areas frequently offer no completely safe direction to point the firearm; if an accidental discharge occurs, there is great risk of bodily injury or property damage.

Before loading, always clean all grease and oil from the bore and chamber, and check to be certain that no obstruction is in the barrel. Any foreign matter in the barrel could result in a bulged or burst barrel or other damage to the firearm, and could cause serious injury to the shooter or to others.

4.0. Ready To Fire

When the rifle is in a "ready to fire" condition the bolt is closed and locked.

• The recoil spring (2) holds the bolt carrier in the full forward position, via the operating rod (1);

• The bolt head (5) is rotated by the control cam (3) of the bolt carrier (4) so that its locking lugs (8) engage in the corresponding recesses of the monoblock (9);

Tension Control Bolt Gun


4.1. Firing

By depressing the trigger (11) the hammer (7) is released. The hammer, under tension from the main spring (12), strikes the firing pin (10) which impacts the cartridge primer (P).

By depressing the trigger (11) the hammer (7) is released. The hammer, under tension from the main spring (12), strikes the firing pin (10) which impacts the cartridge primer (P).

Sig 556 Firing Pin

Caution: Immediately following the firing of a shot, if a subsequent shot is not fired at once, put the safety lever in the "S" (SAFE) position and point the rifle in a safe direction. The safety should be moved to the "S" (SAFE) position as soon as firing is completed, and it should be "on" at all times except when the rifle is targeted and being fired.

4.1.1. Unlocking Of Bolt, Extraction, & Ejection

The gas pressure, generated by the burning powder, drives the bullet up the barrel (13).

As soon as the projectile passes the gas port (15), propel lant gas flows through the adjustable gas valve (14). The gas pressure acts on the operating rod (1) which push es the bolt carrier (4) to the rear.

Sig556 Extractor Pics


During the rearward motion of the bolt carrier (4), the bolt head (5) is rotated by the control cam (3) so that the lock ing lugs (8) are disengaged. The bolt is now unlocked.

Sig556 Extractor Pics

The bolt assembly moves rearward along the receiver rails (16) as far as the stop (17) with the following taking place:

o the recoil spring (2) is compressed; o the hammer (7) is cocked; o the extractor (18) extracts the case from the chamber; and o the ejector (19) ejects the case through the port in the receiver (16).

4.1.2. Bolt Advance

The force of the compressed recoil spring (2) pulls the bolt forward.

The bolt head (5) feeds the next round from the magazine (20) into the chamber.

Sig556 Locking Lugs

In the final stage of the advance, the bolt head (5) locking lugs, via the cam, rotate and lock within the monoblock. The weapon is ready to be fired.

Sig556 Extractor Pics

Keep the muzzle pointed in a safe direction and your finger away from the trigger when cocking any firearm.

Never carry or leave unattended any firearm which is cocked and ready to fire! When cocked, it could fire from slight pressure on the trigger. An accidental discharge could easily result if you fall or drop the firearm, or if the firearm is struck or disturbed by someone or something.

Never fire any firearm with your finger, hand, face, or other part of your body over or adjacent to the ejection port, or in any position where you may be struck by reciprocating movement of the breech. Both the ejection of empty cartridge cases and the movement of the breech are part of the normal operating cycle of firearms, and pose no safety hazard to the shooter if the firearm is held in a normal grip and fired at arm's length.

Never allow other persons to stand beside you where they might be struck by an ejected cartridge case. The case is hot, and may be ejected with sufficient force to cause a burn, cut or injury to an unprotected eye. Make certain there is a clear, unobstructed path for safe ejection of the fired case. Remember, the case may bounce off a hard object nearby and strike you or someone else.

If, while shooting, your firearm develops a mechanical malfunction or binding, or "spits" powder/gas, or if a cartridge primer is punctured or a cartridge case is bulged or ruptured, or if the report on firing does not sound quite right, STOP SHOOTING IMMEDIATELY! It may be dangerous to continue. UNLOAD THE FIREARM - do NOT try "one more shot". Take the firearm and the ammunition to a gunsmith for examination.

While shooting any firearm, an unfired cartridge or fired cartridge case may occasionally become jammed between the bolt and the barrel. Clear the jam as follows, WHILE KEEPING THE MUZZLE POINTED IN A SAFE DIRECTION: Remove the magazine, then pull back the bolt by way of the charging handle and lock it to the rear by pushing up the slide catch. The jammed cartridge or case now can be removed by shaking it out or picking it out.


The bolt automatically opens and shuts quickly while firing. Keep face and hands away from it. Hot brass and powder gas is ejected quickly and can burn you. The rifle should be fired from the right shoulder. Always wear shooting glasses and hearing protectors.


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