Buzzard said:
I was thinking collapsible stock, flat top, no fixed sights, free floating rail. Thinking a short barrel CQB style setup (11.5-14).
I recommend following a guide online with photos, or watching a few assembly videos first so that my instructions make more sense.
So you'll need
stripped lower receiver
- lower parts kit
- carbine buffer tube
- castle nut
- end plate
- carbine buffer
- carbine length recoil spring
- carbine stock
stripped upper receiver
- upper receiver parts kit (ejection port door assembly, forward assist)
- barrel
- barrel nut
- gas tube & gas tube roll pin
- bolt carrier group
- charging handle
- low profile gas block
- muzzle device & crush washer
Step one is assemble your lower. First thing to do is look over your lower parts kit and make sure all your parts are present. Depending on the lower you bought, you may or may not require the trigger guard & trigger guard roll pin.
-Install the mag match
-Install the bolt catch spring & buffer, then the bolt catch paddle and carefully tap in the appropriate roll pin
-Install the pivot pin spring, pivot pin detent and pivot pin (insert from the right)
-Install the trigger guard & trigger guard roll pin if necessary
-Place the trigger spring onto the trigger, insert the disconnecter spring into the top of the trigger and drop the trigger into your lower. Now place the disconnecter into the trigger and hold it carefully while you push in the trigger pin from the side of the lower. It doesn't matter which side the notch on the trigger pin is.
-Install the hammer spring onto the hammer and place the hammer into the lower with the tails of the hammer spring sitting on either side of the trigger on the trigger pin. Install the hammer pin. It doesn't matter which side the notch on the pin is on...only the middle notch on the pin is relevant for the hammer.
-Install your safety (from the left) ensuring that the detent holes on the safety are on the right side of the receiver.
-Install your safety selector detent & spring, then install your grip to lock it into place. As you screw in the grip, watch the safety detent spring to ensure it finds the channel in the grip.
-At this point it would be wise to do a function check. Place your thumb on the hammer and #### it. With the safety off, pull the trigger while blocking the forward travel of the hammer. Hammer release? Check. While holding the trigger down, re-#### the hammer. It should catch on the disconnecter. Feel the click? Hammer retained? Release the trigger now. Hear a click? Hammer retained? Check. Flip the safety to on, and pull the trigger. Nothing happen? Good.
-Install the rear takedown pin from the right.
-Install the takedown pin detent and spring from the rear of the receiver
-Install the buffer catch pin and spring
-Place your castle nut (notches to the rear) onto your buffer tube and screw it all the way back. Place the end plate onto the buffer tube with the indexing nub on its "tail" facing the lower.
-Thread the buffer tube into the lower, carefully watching both the rear takedown pin detent spring and the buffer catch pin. Continue threading the tube in until the buffer tube reaches the buffer catch pin. Depress the catch pin so that it clears the buffer tube and thread the tube in another rotation or two so that the lip of the tube holds the pin in place with the pointed part protruding past the lip. The buffer tube should be as close to the pin as possible without pushing forward on it while the tube remains in the correct upright position.
-Ensure your rear takedown spring has remained in place and push the end plate into the lower receiver to lock it in. Tighten your castle nut finger tight.
-Place your lower into the lower receiver vise block and using your AR combination tool or AR carbine stock tool, torque that sucker down! I don't use a torque wrench for this I just give it a good crank and I haven't had one come loose on me yet. You may use blue loctite on the threads of the buffer tube if you feel that's necessary.
-Take your buffer and recoil spring and insert the tail of the buffer into the spring. Carefully feed the spring into the buffer tube. Once the "lip" of the buffer reaches the buffer catch pin, you should be able to just push it in. No significant force should be required for this. Your buffer will have 3 flat areas on its rounded circumference. Rotate the buffer so that one of these flat areas is overtop of the buffer catch pin and it should move past the pin easily. Once clear of the pin, the pin will rise up under spring pressure and retain the buffer.
-Install your stock on the buffer tube.
Your lower is complete!
Now onto the upper.
-Install the forward assist assembly
-Install the ejection port cover assembly
-Place your barrel into the receiver
-Put anti-seize on the upper receiver's barrel nut threads. This prevents galling and makes barrel removal much easier.
-Place your upper receiver into an upper receiver vise block, and subsequently into a vise. Make sure the vise is clamped/screwed down or you are able to apply sufficient force to the vise to keep it in place.
-Using your barrel nut wrench/AR combo wrench, torque the nut down. As mentioned above, the amount of torque applied can vary, but you want one of the notches in the barrel nut to line up with the hole in the top of the upper for the gas tube. This will require a bit of finesse.
-Install your gas tube into your gas block. Using a roll pin punch to push the gas tube roll pin in makes life easier
-Remove your upper from the vise and install your gas block on the barrel. Take a look down the long axis of your gun to ensure that the barrel nut is correctly indexed. You do not want your gas tube canted to the right or left. Once satisfied, tighten down your gas block set screws. I use blue loctite on these screws.
-Install your free float rail. Depending on the brand, it might require a proprietary barrel nut so you'll have to adjust the instructions accordingly.
-Place your barrel in a set of barrel vise blocks.
Your upper receiver block is not a substitute for barrel vise blocks. Place your crush washer over your muzzle threads with the fat end facing your muzzle device. Tighten your muzzle device down by hand and then, depending on your device, you may use your AR combo wrench or the appropriate wrench to tighten it. I try for 180°-270° of "crush".
* Depending on your barrel length, you may need to install your muzzle device before your free float rail. Be sure to measure how much barrel surface your barrel vise blocks require before proceeding. Always ensure you install your gas block before your muzzle device! It might be necessary to put the gas block on the barrel before installing the gas tube and to place the barrel vise blocks on the portion of the barrel between the barrel nut and gas block. This was necessary for my 11.5" but not my 14.5".
-Install your charging handle into the rear of the receiver. It has nubs on either side near the front that will only permit it to get into its channel at one point in the upper receiver. Find this point and push it about halfway to the closed position.
-Take your bolt carrier group and install it into the rear of the receiver with the gas key riding in the channel on the underside of the charging handle.
-Install your sights/optics, using loctite if you deem it necessary.
Upper complete.
-Install the upper onto the lower with an empty magazine.
-Function check the bolt catch/release.
-Remove the magazine and function check the charging handle.
-Check the safety and trigger assembly all over again.
-Using a snap cap or casing, function check extraction and ejection.
-Using a snap cap or other kinds of dummy rounds to function check feeding.
If I've left anything out, someone chime in. Hopefully I've been helpful and feel free to PM me with any questions you may have or any problems you run into along the way.
The four ARs pictured below were all assembled by me using the tools & methods I listed. All function flawlessly.
