Sigarms Sig SG 550 SP, SG 551 SP Instructions Manual

							 
 
5. Install the gas valve: 

						

							10. Insert bolt assembly: 

						

							3.15 Function check 
 
The function check described below is to be made after every stripping. \
 
 
1. Unload per Section 3.3; 
 
2. Make sure that bolt handle is engaged in correct position; 
 
3. Functions: 
 
a. Safety lever set to “S”, carry out loading movement, pull the 
trigger: 
 

						

							 
3.16. Procedure in case of malfunction 
 
Whenever a SIG SG 550/551 SP no longer works due to a malfunction, 
proceed as follows: 
 

						

							If the weapon still will not fire: 
 

						

							 
4. Maintenance 
 
4.1 Cleaning 
 
The SIG SG 550/551 SP must be cleaned after each period of shooting. 
The following sequence must be adhered to: 
 
 
 
1. Unload weapon per section 3.3.; 
 
2. Field strip the weapon (see Section 3.13.); 
 
3. Clean the barrel and cartridge chamber from the rear. 
 
4. Clean the other parts of the weapon; 
 
5. Lubricate the barrel and chamber using oil or grease; 
 
6. Smear the other parts of the weapon lightly with gun oil or 
grease; 
 
7. Reassemble the weapon in accordance with Item 3.14; 
 
8. Carry out function check in accordance with Item 3.15. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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							5. Function 
 
5.1. Weapon function 
 
5.1.1. Readiness to fire 
 
At the moment of readiness to fire the bolt is closed and locked. 
 

						

							5.1.2. Discharging the shot 
 
By pressing the trigger [11] the hammer [7] is released. The hammer 
is under pressure from the main spring [12] and strikes the firing pin 
[10] which, in turn, impacts against the cartridge primer of the 
cartridge [P] thus discharging the shot. 
 
 
 
 
 
Discharging the shot 
 
 
 
 
 
 
 
 
 
 
 
 
 
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							5.1.3. Unlocking and recoil of bolt 
 
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], \
the propellant gas flows through the adjustable gas valve [14]. The gas 
pressure acts on the gas piston [1] which pushes the bolt carrier to the 
rear. 
 
 
 
 
 
Bolt carrier recoil begins 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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							During the rearward motion of the bolt carrier [4] the bolt head [5] is 
rotated by the control cam [3] so that the locking lugs [8] are 
disengaged. The bolt is now unlocked. 
 
 
 
 
 
Unlocking begins 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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