Disclaimer: I am not liable for any injury to you or others, or damage to your airsoft gun or property, as a result of your assembly or use of the gun according to my instructions. Always be safe and be sure to wear eye protection at all times!
Step 1: Materials and Tools
-the G&P challenge kit (Note that not all parts will be used)
-small mallet/hammer (I used a broken mini Maglite- this will get scratched up if you use one)
-punch tool, or a small metal rod around 3" long
-small steel screw with flat bottom, or metal rod described above
-long nose pliers (you might want two, one that's relatively short, and one that's fairly long and is narrow at the tip)
-screwdriver with a good variety of bits, including philips, flathead, and hex in various sizes.
-metal files (small to medium size, nothing more than 1/2" wide should be necessary)
-sprue cutters/wire cutters
-ink barrel from a ballpoint pen
-scrap of paper (not critical, but helps avoid scratching up the receiver/other parts)
-silicone oil lubricant
-Liquid Wrench lubricant (this is what I used for most of the pins, but the silicone oil works fine too). (I would not use WD-40 for any application in this airsoft gun.)
-clean work area (you don't want to be losing any of the smaller parts)
Step 2: Receiver Separation
Place the receiver so that the body pin overhangs the table. Place your punch tool onto the flat side of the body pin (on the side of the receiver with the Magpul symbol), and tap it with your mallet/hammer until the body pin has slid almost out of the receiver. Repeat for the other pin.
Note that spring-loaded pins in the receiver prevent the body pins from coming completely out. Once you've done this, the upper receiver should lift vertically out of the lower receiver.
Step 3: Trigger Set
Next, put the screw into the front end of the trigger as shown. Then, place the small spring into the notch in the trigger (if you look at it from the top, there is a circular cut out that the spring sits in). Put the other metal piece into the notch, making sure the holes line up and the cut out fits over the spring as shown.
Before inserting the trigger set into the receiver, test how hard it is to fit the pin into the trigger set. If necessary, use a round file on the inside of the trigger. File ONE of the holes of the receiver as shown, this will be the one you insert the pin through. The other hole in the receiver should remain not filed so that the pin stays in place when fully assembled.
Put the trigger set into the lower receiver, making sure the large spring stays against the forward part of the trigger as shown. It may be easier to leave out the flat metal piece at first. Put the pin into the side you filed, but only enough to slide through half of the trigger. Press the metal piece into the rest of the trigger set, then slide the pin further in. You should have to tap in the pin to make it fully inserted.
Step 4: Hammer Set
The two 'prongs' of the spring on the hammer set will rest on the pin used to hold the trigger set in place.
Again, file the hole in only one side of the receiver. Lower the hammer set into the receiver and tap the pin into place.
Step 5: Buffer Retainer/Fire Selector Set
Place this assembly into the back of the lower receiver. While holding it in place, screw it in from the bottom of the receiver with the screw provided.
Using your long nose pliers (the narrower one, if available), insert the small spring into the hole in the buffer retainer set as shown. After that, insert the small pin with the round side remaining outside of the part.
Insert the fire selector into its hole in the receiver, making sure that it is pointed towards semi-auto as you insert it. It will not go fully through, as it is stopped by the spring loaded pin. Use your long nose pliers (again, the narrower one) to hold the pin down as you slide the selector pin fully into the receiver.
Step 6: Fire Selector Set- Part 2
Place one of the spacers and the metal piece onto the pin, as shown. Place the spring against the metal piece, with the longer 'prong' on the side of the piece with the long part projecting from it, and stick the pin halfway through the spring, as shown.
The longer 'prong' will rest on the side of the selector switch that is closer to the front of the receiver. The shorter 'prong' will stick out the top, and rest on the top of the metal piece. Use your pliers to bend the shorter prong towards the front of the receiver, and behind the metal piece. This will cause the spring to bend backwards slightly, which is okay at this point.
Proceed to slide the pin further inwards as far as you can, and tap it completely in.
Step 7: Bolt Catch Set
In my kit, it was necessary to file part of the 'firing pin' and oil it before it could slide freely in the metal block. To test this, hold the metal block together with your hand and try to push the firing pin. If it does not slide freely or spring back into place freely, you need to file as shown in the picture. Once it slides freely, screw the block together with firing pin and spring inside.
Next, place the spring inside the hole in the block as shown. With your sprue/wire cutters, cut off a piece of the pen ink barrel about half a centimeter long. Place this into the same hole as the spring (it should stick out a bit).
Put the bolt catch lever into place as shown, and secure with the included pin. The section of pen barrel should push against the lower part of the bolt catch lever.
Lastly, push the hammer down until it locks into place, and put the bolt catch assembly into the lower receiver as shown.
Step 8: Magazine Catch/Release Set
Next, place the spring onto it through the hole in the other side of the receiver.
Then, push the magazine release button into the hole, compressing the spring. Push it as far into the receiver as you can, and rotate the magazine catch in order to screw it into the magazine release button, as shown. You may need to put something between your finger and the magazine release button so that you can push it in far enough to screw the magazine catch on completely.
Step 9: Buffer Tube and Buffer Assembly
Screw the buffer tube into the back of the lower receiver, until it doesn't screw in any further, then unscrew until it is aligned correctly, as shown. Screw the ring into place, securing both pieces against the receiver.
Place the buffer into the spring, and place both into the buffer tube. These will be held back by the buffer retainer set as shown.
Step 10: Forward Assist
Secure them together with the pin provided, making sure that the spring does not come out of place as you do so. It may be helpful to hold the pin with pliers as you tap it in.
Slide the large spring over the whole assembly. Place it into the upper receiver as shown.
Test which hole the pin fits easier into by hand (top or bottom). While holding the forward assist in place, tap the pin into place. It may be helpful to have someone else depress the forward assist while you tap in the pin.
Step 11: Ejection Port Cover
Put the pin through the hole in the receiver and halfway through the ejection port cover as shown. Put the spring in place, with the longer 'prong' on the right side, and resting on the ejection port cover. Push the pin completely through.
The pin has a short section that is narrower than the rest. The small ring will fit over this, between the receiver and ejection port cover. This is to ensure that the pin does not slide out. This may be necessary on the left or right side of the ejection port cover.
To test which side, close the ejection port cover. Check which side has more space. If necessary, pull out the pin and put it in the other way around so that the narrower section aligns with the space between the ejection port cover and receiver.
Place the ring on that narrower section of the pin, between the ejection port cover and receiver. Put a small scrap of paper behind it, so that you don't scratch the receiver with whatever you use to tap the pin in place. Use a small steel rod or screw with your hammer/mallet to tap it into place. It should only require one, quick tap.
Step 12: Bolt Assembly Part 1
Place the largest O-ring onto the second largest plastic part. Push the pin into the plastic part halfway, so it protrudes partly into the inside as shown.
Straighten out a paperclip, and bend the end into a right angle. Use this to hook the end of the spring through the plastic part, and place onto the section of the pin protruding into the inside. Then, push or tap the pin the rest of the way in quickly, so that the spring does not fall off the pin.
Place the other spring onto the small narrow plastic part as shown. Place the two small plastic parts into the largest plastic part.
File the end of the largest part a little bit, so the other assembly fits better. Insert the second largest part (the one with the O-rings) and secure with the pin as shown.
Step 13: Bolt Assembly Part 2
Lock it in place with the rectangular plastic part included. Note the two nubs on the bolt carrier- you will need to file parts of the plastic part as shown so it is relatively flush with the rest of the bolt carrier.
Use the locking ring on the small metal part from the nozzle assembly. Again, it's usually good to put a piece of paper behind it to avoid scratching the part. Use your metal rod/punch tool/screw with mallet/hammer to tap it into place.
Step 14: Charging Handle/Finishing Bolt Assembly
Slide both into the upper receiver (it may be helpful to oil everything before you do so).
Step 15: Inner Barrel and Hop-Up Assembly
Place the smallest O-ring into the indent on the outside of the barrel. Place the hop-up bucking next. The rectangular indentation on the outside of the barrel should be directly above the gap on the end of the barrel (If you look in, you should see a small rubber bump protruding where the gap in the barrel is).
Place the barrel inside the hop-up assembly, making sure the rectangular protrusion on the hop-up bucking fits inside the indentation in the steel hop-up assembly.
Put on the other half of the hop-up assembly and secure with the two largest O-rings.
Place the hop-up dial onto the barrel as shown, followed by the remaining O-ring (second smallest).
Push everything into the hop-up casing, making sure the protrusions from the hop-up assembly fit into their respective indentations in the hop-up casing.
Step 16: Delta Ring
Place the piece with a gear-like shape through the top of the delta ring (the smaller end) so that one of the indents lines up with the hole.
On the other side, place the spring, so that the gap lines up with the holes.
Place the locking ring onto the groove in the piece that has a gear-like part. Make sure the gap lines up with the holes. This can be done by holding one half in place with your hand, and using a flathead screwdriver as a kind of lever to push it in place. Repeat with the other half of the ring.
Step 17: Front Sight/Barrel Assembly Part 1
Secure with the pin provided (oil may help here).
Insert the inner barrel with hop-up assembly into the outer barrel, so that the protrusions from the hop-up casing fit into the indentations in the outer barrel.
Step 18: Barrel Assembly Part 2
Slide the delta ring onto the outer barrel, and tighten it by rotating the gear-shaped piece. You may have the tool to do this, I didn't.
Align the gaps in the gear-shape, the spring, and the locking ring. This can be done with several methods: with a paper clip (only works for spring), long-nose pliers for the locking ring, or your steel rod/punch tool.
Step 19: Attaching Front Sight Assembly/Handguard Cap
Slide both of these onto the outer barrel, and thread the gas tube through the holes in the delta ring and upper receiver.
Rotate the front sight a little bit until both holes in the bottom are clear of obstructions.
Tap the pins through the holes in the front sight, attaching it to the outer barrel. Make sure you tap them in smooth end first. Some liquid wrench or silicone oil might be helpful here.
Step 20: Flashhider
Place the thick steel ring over it, with the lip facing inward, so the O-ring is partially covered.
Screw on the flashhider. If you use the orange plastic one, use the small screw to secure it in place.
You may find that the flashhider is not positioned as you like when it is fully tightened. If you want, you can use the metal spacers between the steel ring and O-ring so that the flashhider is positioned correctly when fully tightened.
Step 21: Joining Upper and Lower Receiver
Arrange the upper and lower receiver so that the body pins stick upwards (not like the first photo). Push the upper receiver downwards into the lower receiver.
Tap the body pins into place while making sure the upper receiver does not move. It may be helpful to oil the pins as shown so they slide easier.
Step 22: Handguard Assembly
Place the semi-circle protrusion on the front of the upper half of the handguard into the handguard cap. Pull down the delta ring with one hand, and press the rear side of this half of the handguard into the delta ring.
Repeat for the lower half of the handguard.
Step 23: Stock
In order to make this happen, I found it useful to put a sort of spacer between the lever you press and the pins it presses in turn.
I would recommend an allen wrench (if it's large enough), or a screwdriver bit (again, if large enough).
You can put either of these in place by pressing on the pin from the inside with your finger, than putting the spacer in place with your other hand.
Use your thumb to prevent the spacer from slipping out, press on the lever, and the stock should slide smoothly onto the buffer tube.
Step 24: Pistol Grip
If your pistol grip fits on, then the best way to put it on is to put the screw on top of your screwdriver, then put the grip onto it and screw it into the receiver. Don't forget to put the storage compartment cover back on.
However, mine did not fit, as some of the ridges on the inside of the grip were angled inwards, preventing it from sliding on. This can be solved by lightly filing the upper part of those ridges (mine were tapered, and the lower halves were fine). Note that you don't want to make the fit too loose, so that the pistol grip is securely held to the receiver.
Step 25: Rear Sight
Slide the rear sight onto the receiver's rail, while holding the hex nut in place in the back.
Tighten the screw.
CONGRATULATIONS!!! You have completed assembly of your challenge kit.
Step 26: Operation
The rear sight allows for two different apertures. The first is when two parts are closed, and gives a smaller aperture. If you pull forwards on the little tab on the top, the two parts will separate and you get a larger aperture. Which one you use is really personal preference. The larger one may be better for low light situations, or if you need to sight in super super quickly, but may be a tiny bit less accurate depending on how good of a marksman you are.
Put on eye protection. If anyone is watching, give them eye protection too. Guys, it's your eyes, and you only have two of them.
Hold the magazine upside down, and place the nozzle of your green gas can into the brass hole in the magazine. Press it down for about 5 seconds (the sound of the gas flowing should stop).
Load 6mm airsoft bbs (I recommend .20's. Seriously guys, it's a gas gun.) into the top of the magazine. This can be done by hand, or with a speed loader. If you use a speed loader, you'll need to put your finger against the front of the mag so the bbs don't just fall out the front.
Put the magazine into the magwell, and push upwards until the magazine catch clicks into place. Pull back the charging handle as far as it will go (you'll need to pull back on the small lever on the side of the charging handle), and release it so the bolt slides forward. If it doesn't slide forward, refer to the next step (Troubleshooting).
If the bolt slides forward, you're ready to fire. Shoulder the rifle if you haven't done so already, select semi or full (I strongly recommend a few rounds on semi before going full), and pull the trigger. If the gun fires, but the bolt stays back, refer to the next step (Troubleshooting).
When the mag is empty, the bolt should catch when it is back in the buffer tube (you can't see much of the bolt through the ejection port). Hold the mag and press the mag release button to remove your magazine.
If you have only one mag, wait for it to heat up a little bit to room temperature before you reload it with gas and bbs. If you have another mag, you can now put it in the magwell, press the bolt release lever to let the bolt slide back into place, and continue firing.
Step 27: Troubleshooting
To prevent this, you can place spacers inside the buffer tube before putting in the spring and buffer so that the buffer/bolt do not slide as far back in the buffer tube. People commonly use several quarters, but I used two rubber hose washers and one quarter (the one quarter is necessary so the buffer actually contacts something). You may need to trim some extra rubber from the sides of the hose washers if you use those. Don't use a nickel like in the picture, as it is a little too small.
Just unscrew the ring on the buffer tube, and unscrew the buffer tube from the receiver. Be careful, as the buffer and buffer spring will want to come out of the buffer tube. Remove the spring and buffer (preferably not by letting them shoot across the room :P). Place the spacers you want to use inside the buffer tube, or on top of the spring, then place everything into the buffer tube.
Screw the buffer tube back into the receiver and screw the ring back into place.
If you hear the spring rattling in the buffer tube after firing a shot, that's normal. If you don't want it to make as much noise, I will post shortly how I will 'fix' this.
EDIT (October 8, 2013)- I've found a way to get rid of the noise in the buffer tube caused by the buffer spring ratting around. You only need a bit of teflon tape, that thin white tape about 1/2 cm wide used to seal the threads on pipe connections. I wouldn't recommend anything thicker, as it may hinder the movement of the buffer spring or cause it to get stuck.
Tie the end of it to one end of the spring, and wrap around the rest of it as shown in the pictures. I found that the best way to wrap it is to rotate the spring, and move the tape around the section of spring you are wrapping. Don't worry if it gets twisted, but try not to wrap more than one layer on any given section of the spring. If you can get it to stay untwisted, you can cover a bit more surface area with less tape.
Before reinserting the spring, make sure that the ends of the spring are not in a position to scratch the inside of the buffer tube. You can file them down if you wish just to be sure. Be sure to check the tape fairly frequently, as the teflon tape will wear down over time.
Thanks for viewing my instructable!! I'm not asking you to favorite or subscribe -okay, yes I am-, but I hope you enjoyed building this rifle as much as I did! Feel free to comment below with questions, concerns, constructive criticism or anything else you feel the need to express.