Step 1: This is what you Sig 552 airsoft rifle AEG looks like completely assembled.

Step 2: Remove the magazine by pulling back on the mag release lever.

Step 3: On the front left side of the Sig 552, there is a screw head, with a flat head screw driver loosen and remove this piece.  This piece is just behind the front fore grip and the front of the receiver.

Step 4: From the other side, remove the entire pin.  This is also required to change your battery.

Step 5: After you have removed the pin, carefully yet firmly pull back on the bottom part of the fore grip.  This will allow the top and the bottom to seperate.

Step 6: Lift up on the top part of the fore grip and remove it.  Do the same to the bottom part of the fore grip of your Sig 552.

Step 7: Remove the battery from it's 'compartment', unclip it and set it aside.

Step 8: Move to the rear of the Sig 552 airsoft rifle and push the button that allows the rear folding stock to fold.

Step 9: Inside of the folding stock you will see a Phillips head screw, loosen and remove it being careful not to loose it or get it 'mixed up'

Step 10: Move to the bottom of the pistol grip and loosen and remove the two screws that hold the plate that holds the motor in place.  Be sure to remember which one goes where, they are different sizes.

Step 11: Disconnect the wires from the motor.  Be sure to remember it orientation because the wires are suppose to go a certain way.  Also notice the 'red' mark on the motor, the red wire goes on that pin.

Step 12: With a pair of needle nose pliers or something similar, pull out the motor.  It is going to feel as if it is 'stuck' but it will come out with a little pressure.

Step 13: If you look inside of the pistol grip, you will see two Phillips head screws, loosen and remove them.  Sometimes they don't come all the way out, just make sure that they are loosened all the way.

Step 14: Carefully lift up on the pistol grip and pull it out enough to dislodge it from the mech box.

Step 15: You will notice that the motor wires go through the forward most 'slot' inside of the pistol grip, remember this because the other two 'slots' are for the motor alignment bracket.

Step 16: This is what it should look like after the pistol grip is completely removed.  Notice how the wires are run along the mech box.

Step 17: On the right side of your Sig 552 towards the rear near the folding stock you will see another flat head 'screw head'.  Loosen and remove it.  Remember which side it came from.

Step 18: Do the same on the other side, notice that this one is different.

Step 19: Carefully yet firmly, pull off the rear folding stock.  This is what you should have left.

Step 20: Now move back to the front fore grip area, notice that there are some zip ties holding in the battery fuse, or at least there should be.  Cut them, being careful not to cut the wires.

Step 21: This will allow you to pull the battery connector through the hole.

Step 22: Open the fuse holder casing and disconnect the fuse so that the casing is seperated.

Step 23: Just forward of the lower receiver, is a Phillips head screw, loosen and remove it.

Step 23: Carefully pull forward on the upper barrel assembly, about 1/2 inch.

Step 24: Flip the gun over and look inside the lower receiver where the magazine is loaded.  You will see a Phillips head screw, loosen and remove it.  It is securing a plate that holds the hop up in place, ultimately holding the upper receiver in place.

Step 24: With a small flathead screw driver or something similar, pull up on the 'plate' to release the upper receiver and barrel.

Step 25: This will now allow you to completely remove the upper receiver.  BEFORE you pull it all the way off though, be sure to dislodge the wires for the battery.  They can be easily dislodge through the upper receiver.  You will know what I am talking about when you get to that point.

Step 26: So now this is what you should have.

Step 27: On the bottom of EACH selector switch, is a small Alan head screw.  Loosen and remove each one.  Remember which switch came from which side.

Step 28: Under EACH selector switch is another plastic alignment tab.  Inside that tab is Phillips head screw.  Loosen and remove those.. REMEMBER which one came from which side.

Step 29: You will notice a 'gear' on each side of the mech box just behind the trigger.  Try not to move this gear.

Step 30: Carefully begin to pull the mech box out of the lower receiver.  You may have to 'spread' the receiver a little to clear the gears inside.  NOT TOO MUCH but just enough to remove the mech box.  The gears are held in place by the lower receiver, so they will fall off of the mech box once it is removed unless you hold the gears in place as you pull it out.  It is kind of hard to explain, so if you are not comfortable with this step, I recommend you STOP NOW and hand it off to someone with more experience.  Sorry no pics..

Step 31: Once the mech box is out of the lower receiver, the gears on the left side of the gear box will look like this.  Notice the marks on the gears.  These are timing marks similar to a cars timing belt marks on a cam sprocket.  They need to be in the same orientation.

Step 32: Here is a look at the gear on the right side of the mech box.  Notice that they have timing marks as well.  These marks are for the selector switch and if they are 'timed' wrong, then your Sig 552 will not work correctly.

Step 33: As you pull the gears off of the mech box, take notice of how they are placed on the mech box.  It isn't too hard to figure it out, but remember anyway, it will go a bit faster on reassembly.

Step 34: Here is what you are left with.. the mech box and the lower receiver.  Finished.

* Technicians note*  If you are not mechanically inclined, I HIGHLY RECOMMEND that you do not attempt this disassembly.  There are a lot of things that can go wrong if it is done incorrectly.  858airsoft.com is NOT responsible for damages occurring from use of this information.  This step by step is offered as a GUIDELINE ONLY and it is your responsibility to make sure that each presented step is significant to your particular airsoft gun.  Please do not email us asking for assistance as we do not have the time to reply.