Building the AR-15 Upper

Building the AR-15 Upper

This is a discussion on Building the AR-15 Upper within the DIY forums, part of the Sniping Related category; Brother Kenny showed me how to assemble the AR-15 upper receiver assembly. So I thought I should spread the word a little bit further. First ...

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  1. #1
    Senior Member madgunsmith's Avatar
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    Building the AR-15 Upper

    Brother Kenny showed me how to assemble the AR-15 upper receiver assembly. So I thought I should spread the word a little bit further.

    First of all, Brother Kenny says that you should always remember, "CRAB". "CRAB" stands for Colt, Rock River Arms, Armalite and Bushmater. Only use parts made by these makers and you will never go wrong.

    To build an AR-15 upper receiver you need the following parts: Upper receiver, ( Brother Kenny specifically recommends Rock River Arms Uppers; he says RRA parts are really nice) you also need a bolt carrier and bolt, charging handle, gas tube, delta ring, weld spring, snap ring, barrel, hand-guards, gas tube pin and flash suppressor.

    Brother Kenny likes Bushmaster's chrome line barrels when it comes to a general purpose rifle. He likes the RRA enhanced bolt carrier because this bolt carrier affords more protection for the firing pin.

    Anyway, you can buy all the parts one piece at a time. You can buy the parts over a period of time and this way you won't notice the cost.

    Here are two of Brother Kenny's favorite AR parts sources.

    http://www.ar15sales.com. Phone 1-603-770-2281 and ask for Pete. Pete is one of the largest Rock River Arms dealers. He is a wonderful, honest gentleman.

    http://www.eaglefirearms.net. Phone 1-303-655-0268. These guys are another first class outfit. They carry Rock River parts as well as Bushmaster parts.

    Here's what you need to assemble it and here's how to do it. You need the following tools and supplies:

    1. Receiver blocks--Brownells part no. 702-003-015--$43.75
    2. DPMS action wrench--Brownells part no. 231-000-007--$36.50
    3. wheel bearing grease--available from Walmart for $2 to $3
    4. Roll pin punch--Brownells part no 231-100-001--$3.75
    5. dishwashing gloves--steal these from the wife
    6. vise--cheap vises can be had at Harbor Freight
    7. barrel blocks, or piece of rope-(barrel blocks--Brownells part no: 852-015-000--$55. Note barrel blocks are optional.)
    8. #16 drill bit. try http://www.mscindustrial.com
    9. Snap ring pliers--available cheap from Harbor Freight

    Check out http://www.brownells.com

    The receiver blocks are made of polymer and can be found in the Brownells catalogue. The action wrench is also available from Brownells and so is the roll pin punch. You can buy a #16 drill bit at Brownells or at any good tool store. Brownells also carries an expensive set of barrel blocks, which you really don't need. You can get by without them.

    Anyhow, tomorrow, I will continue on with the explaination.

    Stay tuned and don't go


    Mad

  2. #2

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    I cant say I agree with the CRAB rule mabye DRAB... (DPMS replaces colt... cause colt blows. )

    But im looking foward to this one.

  3. #3
    Senior Member madgunsmith's Avatar
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    So it is still today and not tomorrow. I will continue anyway.

    First of all take a look at all of your parts. Notice how the AR-15 upper receiver has a notch right in front of the gas tube hole. Notice also that at 12 o' clock on the barrel extension, there is a metal stud. This stud is called the barrel indexing pin.

    Anyway, the barrel fits into the receiver so that the barrel stud engages against the receiver notch. Notice that the upper receiver is also threaded. There is a collar-like fastener attached to your new barrel and this part is called the barrel nut. The barrel nut screws down over the threaded upper receiver and in so doing it clamps down on the barrel thereby holding it in place.

    So go ahead, put a little Break Free on your barrel extension. Just a drop or two will do the trick. Then insert the barrel into the upper receiver so that the barrel stud engages the receiver notch. Tap the barrel into place using a rubber mallet. Gently does it. Tapping the barrel into place will give you a visual understanding about how the barrel and receiver should fit.

    Now smear a little wheel bearing grease on the receiver threads. Take the barrel nut and gently thread the barrel nut so that it tightens down over the receiver thread.

    Take a good look at how everything fits together, then loosen the barrel nut and carefully remove the barrel from the upper receiver.

    We are now ready to assemble everything for real.


    Mad

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  5. #4
    Senior Member madgunsmith's Avatar
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    First you need to assemble the barrel nut assembly. The barrel nut assembly consists of the barrel nut, delta ring, weld springs, and snap ring.

    The delta ring is just the handguard retaining ring. The weld springs supply handguard tension and the snap ring retains the entire assembly.

    Here is how to install the barrel nut assembly.

    1. Pass the delta ring forward from the chamber end of the barrel. Make sure that the tapered end of the delta ring faces towards the muzzle.

    2. Push the tapered end of the delta ring over the back end of the barrel nut.

    3. Place the weld spring assembly over the barrel nut shank.

    4. Install the snap ring behind the weld spring. Push the snap ring forward so that it compresses the weld springs, and use snap ring pliers to snap the ring around the barrel nut shank.

    Your barrel nut assembly is now assembled.

    This procedure takes less than 2 minutes to do. Unless you are

    Mad

  6. #5
    Senior Member madgunsmith's Avatar
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    Installing the flash suppressor:

    Install your expensive barrel vise block around the barrel. Clamp the vise blocks and barrel securely within a bench vise.

    Alternatively, wrap a length of rope tightly around your barrel. Clamp the rope protected barrel securely within the jaws of your bench vise.

    Place a crush washer over the muzzle threads. Make sure that the tapered end of the crush washer faces the muzzle. Tighten the flash suppressor by hand as far as possible.

    Take the DPMS barrel wrench. Notice that this wrench also has a wrenching slot for the flashing suppressor.

    With the barrel securely fastened within the vise, use the wrenching slot to tighten the suppreser firmly into place. Don't be afraid to use a little muscle. If you are using an A2 suppressor, make sure that the bottom of the suppressor is properly timed. (When properly installed, you will have no slots at the barrel's 6 o' clock position.) If you are using an A1 suppressor, just tighten it so that the wrench flat lies in the horizontal position.

    Installing the flash suppressor is easy. It will take less than 3 minutes to do.


    Mad

  7. #6
    Senior Member madgunsmith's Avatar
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    Now we are getting ready to install the barrel:

    Slide the barrel into the upper receiver so that the barrel stud engages the receiver notch. Smear a little wheel bearing grease onto the receiver threads.

    Place the receiver inside the Brownells receiver block. The block is a clam shell type of arrangement that encases the receiver. Once the action block is securely wrapped around the receiver, clamp the block between the vise jaws.

    Spread a little wheel bearing grease around the receiver threads. Grasp the barrel nut and tighten it over the receiver using hand tension.

    Once your barrel nut is hand tight, take the DPMS barrel wrench. Align the teeth of the barrel wrench with the teeth of the barrel nut. While pushing in towards the receiver, turn the barrel nut using firm pressure. Tighten the barrel nut so that it is snug.

    Loosen and tighten the barrel nut two more times.


    We are almost finished.



    Mad

  8. #7
    Senior Member madgunsmith's Avatar
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    Once more tighten the barrel nut by hand. Take the gas tube and gently insert it from the rear into the receiver gas tube hole. Take a look right in front of the receiver gas tube hole. Notice the weld springs and snap ring.

    Use a small screwdriver to align the weld spring and snap ring. They are aligned so that the gas tube can slide through. Slide the gas tube through the snap ring and weld spring. Rotate the delta ring so the the delta ring hole is aligned with the 12 o clock position of the barrel nut.

    Be very careful not to allow the gas tube to pass beyond the delta ring. If it does so, you can damage the gas tube when you rotate the barrel nut.
    The front of the gas tube should merely peek through the rear of the delta ring. It does not pass completely through.

    Use the barrel wrench to tighten the barrel nut. The barrel nut should be tightened firmly. Just a little bit tighter than snug. When the barrel nut is correctly orientated, you will be able to see the gas tube perfectly aligned with the barrel nut hole.

    Remove the gas tube. Take the #16 drill bit and use it as a gage. Slide the drill bit between the barrel nut, delta ring, weld springs, snap ring and receiver. If the drill bit slides back and forth freely, then you have installed the barrel correctly.

    Now is also a good time to bore sight the upper receiver. If you have installed the barrel properly, you should be able to confirm your sighting.

    If you can't get the barrel nut to line up properly at first, don't panic. Keep tightening and loosening the barrel nut and eventually it will line up properly.

    The next step is to install the gas tube and handguards.



    Mad

  9. #8
    Senior Member madgunsmith's Avatar
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    Installing the gas tube:


    Place some protective masking tape over the right side of the front sight block.

    Put on the rubber dishwashing gloves as you need all the grip you can get when it comes to foolling with the gas tube.

    Rest the gas tube against the right side of the front sight block. Make sure that the gas tube is correctly orientated. The gas tube is drilled for the retaining roll pin and this side of the gas tube must be nearest to the muzzle.

    Slide the gas tube forward against the front sight block and then slide the gas tube through the barrel nut assembly and into the upper receiver. Once the rear of the gas tube is inside the upper receiver. grasp the front of the gas tube and pull it forward. Insert the front of the gas tube into the front sight block and make sure that the gas tube hole faces down over the gas port.

    Align the gas tube so that the gas tube roll pin holes line up with the roll pin holes on the side of the front sight block.

    Pick up the roll pin with a toothpick and start it into the front sight roll pin hole. Use the roll pin punch and a small hammer to gently tap the pin home.


    The gas tube is now installed.

  10. #9
    Senior Member madgunsmith's Avatar
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    Push back on the delta ring and install the handguards. If necessary get a buddy to help you push down on the delta ring. You may also tap the handguards in place with a rubber hammer. But gently does it.

    Take the bolt carrier and slide it back and forth inside the upper receiver. If you have done everything correctly the bolt carrier will slide back and forth effortlessly. If the bolt carrier key binds against the gas tube, then something is wrong. But if you take care and use quality parts, this won't happen.

    If the bolt carrier slides back and forth freely, then you are good to go.

    Check the bolt carrier to ensure that the key is securely staked and check to see that your bolt gas rings are staggered. Then you are good to go.


    Mad

  11. #10
    Senior Member madgunsmith's Avatar
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    Headspace and the AR-15.


    You cannot adjust the headspace of the AR-15. The headspace is set at the factory when the barrel extension is installed. If the barrel extension is properly installed, then you are set.

    Just make sure that you use a quality barrel and a quality bolt. That way you will be fine.

    It doesn't hurt to use headspace guages to check your upper receiver assembly. But it really isn't necessary. If you build your upper receiver with quality parts, you can shoot the thing right away without worry.


    Mad

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