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Hey guys. Josh Kent with US Arms Here to bring you another video on the AR 15 platform through us. Today we’re gonna show you how to build the upper receiver group. Okay, so in this video we’re gonna talk about the parts that you’ll need to build, the upper receiver, the tools that you’ll need, and we’ll go through some of the little nuances of assembly that are gonna bring you the most accurate rifle that you can build with the parts and products that you have.


And then we’ll take you through the steps of building the upper receiver. Stay tuned with us and thanks again for coming back. Okay guys. First we’re gonna cover the parts. , in order to build a US Arms upper receiver, and most of your standard AR 15 upper receivers, so I’m gonna start from the right here and work my way over to the left.


So first off, we have a barrel nut right here. Okay? You’re gonna need a barrel nut. We’re going to need a US arms upper receiver group. Our dust cover, our bolt carrier group charging handle. We start here at the top. This is a mid length gas. Our gas tube roll pin, slac phosphate gas block seven 50 to match the outer diameter of the barrel.


Here we have one in seven US arms barrel. We have the retaining screws for the hand guard for the upper receiver, a retaining band for that’s gonna go into the barrel nut for the hand guard. And we have our 15 inch hand guard. These are the. As, , for a standard upper receiver group that you would need for assembly.


All right, guys. At this point we’re gonna talk about some of the tools that you’re going to need for assembly. We’re gonna start from the right here. We have a 5 56 NATO go gauge. We will need a 5 56 nato no go gauge, and we’ll talk about the reasons for that nylon hammer or mallet. We have a torque wrench set in foot.


We have a torque wrench here set in inch pounds. We have a marking for 75 inch pounds for the hand guard screws Here we have a long punch, a short fat oversized punch, a five 30 seconds T handle,  Allen wrench, a three 30 seconds Allen wrench, and a gas block assembly block. These are the minim tools that you’ll need for assembly.


The next step, we’re gonna take you through the assembly process and some of the nuances that to make and build the best upper receiver group on the market. Thanks. Okay guys, now we’re gonna go on into the assembly process and all of the steps needed to finish and there’s not many, but to finish the upper receiver group.


Okay, so the first thing I want to do, once I know that I have all of my parts here in front of me, the first thing that I want to do before assembly is I want to check the head space of the barrel that I. With certified gauges. Here we have Pacific Gage in Tool 5 56 NATO Go and no go gauges. , there are different gauges.


You have 2 23 Remington. You have 5 56 NATO and 2 23 wild. The only real difference between them is the free boar space out in the front, but the overall chamber length is going to be the same. So here we’ve just used standardized 5 56 NATO gauges. Okay, so the first thing I wanna. I’ve already went ahead and cleaned the chamber on this US arms barrel so that I have all of the debris, any oil, anything like that that would build up to give me a, a shorter head space.


So I have just basically bare metal chamber in this barrel so that when I check the head space with these gauges, I have metal to metal contact and I have a true dimension spec set for that barrel. So what we’re gonna do is we’re gonna go ahead and disassemble this bolt carrier. . So by removing the firing pin, retaining pin, I’m gonna set this down here, drop the firing pin out, which will now allow me to rotate and remove the cam pin here on the bolt.


And sometimes these things don’t wanna come out quickly, but there’s our cam pin and our bolt is now in hand. Now you do not have to do this, but it’s gonna make it easier for you if you just go ahead and remove.  extractor on the bolt. So you have your extractor pin and your extractor will come right out.


Ensure that you have for your bolt, ensure that you have the, , extractor spring and an if you have the additional donut, that’s great. It gives a little more grabbing power, but you don’t necessarily need it right off hand. But just make sure that you have a spring there to give you, , your extractor a good bite on the round when you go to shoot or re.


So when you have this bolt in hand, you will have a bolt, the ejector, you can leave it in there and a strip bolt. So as we move forward, I want to take and, and set this barrel to where I can get ahold of it. I’m gonna set my bolt here and I’m gonna go ahead and set out my go and no go. Gauges put them right there.


Now the gauge is used to check the overall headspace from the. , which is going to be from the shoulder of the case here to the base or, or face of the case. So this is, is set that we’re checking basically the head space from the, the face of the bolt to the shoulder of the chamber. Okay. So if we take a look at a go and a no-go in, in thousands, the the red, the no-go is going to be slightly larger than the.


and if we were to continue forward to an even bigger chamber, we would have a field gauge, which we’re not gonna check here. So what we should have is a bolt that drops on the go and not rotate into battery or drop on the no-go, which is gonna give us that nice tight chamber that we need, which is gonna produce good accuracy for us.


Alright, so I’m gonna grab a T handle, a little delrin handle. To maintain positive control of this bolt. Again, I have cleaned the chamber, so we have a good clean chamber here. I’m just gonna take this, go gauge and drop it in, ensure that there’s nothing on the gauge that it’s clean. Drop it in place. Now I can press with just a little bit of pressure on the ejector, and I rotate that bolt into the barrel extension.


A lot of people call it a star chamber, but it’s actually called a barrel. So that has locked in the battery. I can now pop that loose, drop that gauge in hand, don’t let it fall on the concrete. Now I take my no-go. I drop it in place again, ensuring that the, the gauge is, is clean and I press down and I try to rotate this in the battery and it should not.


Okay? So that means that I’m not able to turn this and rotate it into battery. So that means that our headspace for this. Is going to be exactly where we want it and it’s a good match Headspace, and we’re now able to continue forward with this barrel and assemble it with this bolt and bolt carrier group.


Alright guys, step one is going to be taking the upper receiver group, alright, and we’re gonna go ahead and put our dust cover on. So if we take a look, we have a two captured areas. We have one on the front of our upper receiver and to the rear our dust. What we have to do is we have to maintain spring control or spring pressure positive, , pressure with this spring.


This flat edge here needs to go and rest against the body of the upper receiver group. So what we have to do is we have to rotate that spring back in place. We’re gonna, we’re gonna hold it with our finger, press it as such, insert the front, and then towards the rear of the receiver, we can take our. To press that back leg in, and once we feel it lock, we can release that spray against the upper receiver group.


And now we have spring tension on the dust cover. That’s step one, step two, we’re gonna take the barrel and we’re going to lock in place our location pin, which goes to the 12 o’clock position right here in the recess of the upper. And the tighter the fit between the barrel extension and the upper receiver.


Sometimes you may have to work this back and forth. This is a pretty tight fit and if it’s, if it’s super tight, but you could still get it in by hand pressure, that is a good thing. The next thing you want to do is grab a rubber mallet and just seat. Give it a couple of taps and have it seat. Once you see metal to metal contact between the barrel.


And the face of the upper receiver, you’re good to go. Okay, guys, the next step we’re gonna do this is optional for you. Okay? But we, we suggest it because as you shoot barrels, barrels get shot out and then it’s easier to replace the barrel and also get a better torque standard on our thread. If we apply a little bit of anti seas lubricant, a little bit of silver lubricant, it doesn’t take much.


And while it’s set up here in our vice, On our upper receiver mandrel, we can take this and just dab a little bit into the threads. You don’t wanna get any on the face of the, , the, , barrel extension, so just be mindful of that. Alright, we’re just gonna place some right there in the threads. And then as we run our barrel nut up, we’re gonna allow that to spread this throughout the thread.


Now what this does for us is, as it builds, , if we didn’t put it on there, we, we would build up friction between the barrel nut and the upper receiver thread. Now that friction is gonna keep us from getting a true torque spec. So as we set the torque spec, which here we set it at a hundred foot pounds.


Alright, as we go to thread this on, we can work this back and forth in through the. So that it, it loosens the friction between the barrel nut and the upper receiver, and it gives us a true torque spec. Also, later on down the road, when we shoot this barrel out, we’re able to remove the barrel nut easier and, , replace the barrel at the end user level.


So after running the barrel up by hand with a little bit of anti seas on there, moving it around, getting the, the barrel nut to kind of spread around the threads, once we get it tight by hand, we’re gonna. Our torque wrench, and again here, the spec for us in-house is a hundred foot pounds. To set the barrel nut with the, , with the upper receiver, a lot of companies will torque them to 32 to 40 foot pounds.


And the reason why we torque ours at 101, we have 70, 75 billet upper receivers. The metal’s super.  and we’re able to do so. We’ve toed these to right at 140 foot pounds with no issues just to see if they’d break. , so a hundred foot pounds is gonna be plenty. We also run a fully free float hand guard, and the gas tube is also fully free floated.


So we tor these a little bit more so that you never have to worry about your barrel coming loose or your hand guard coming loose. If you were to purchase a US arms up a receiver group, or. . So we’re gonna go ahead and set this to a hundred foot pounds. And for this torque right here, if you take a look, we have zero, 50, a hundred.


So we’re gonna set this at the a hundred foot pound mark, and as we set it, or you guys go to set anything for the barrel nut, you always run it up slow. And as you stage on your mark that you wanna set it at, whether it be 40, 50, 60, a hundred for us as you. I want you to get to that point and then hold for a few seconds to allow anything between the barrel nut and the threads of the upper receiver to settle.


Okay? So I’m gonna show you guys that. So as we apply our wrench, we’re just gonna run it up. And again, this is as far as you can go by hand. You’re gonna go ahead and set this with the wrench. All right, so I’ve hit the wall there. I’m gonna set it and now I’m going to pull slowly watching my. Pull to a hundred stage for a couple of seconds and lean off of it.


So once I’ve held for a few seconds at a hundred foot pounds, which is our mark I’ve set, and now this barrel nut is set to a hundred foot pounds, I’ve t taken away any possibility of like a friction lock, which would give me a false indicator of the torque between this barrel nut and this upper. So once you stage and hold for a couple of seconds, you’ve kind of led any mechanical energy that you’re delivering into that barrel nut to kind of settle and actually set this thing at the prescribed mark.


So from this step, we’re gonna go into building the gas block and gas tube. Okay guys, the next step, once we put our barrel on and torqued our barrel nut, we now have to assemble our gas system. All right, so we have a, a s. Phosphate gas block with a 750 thousandths, , id, the outside diameter for this barrel, if you take a look here, is 750 thousands.


So we have to have, , obviously a gas block that will fit it again. The next thing you wanna pay attention to is the length of the gas system. This is a mid-length gas system, and this is a mid-length gas tube. So if we look at it, one of the easiest ways to make sure that you have the, the, the correct length.


If you were to match up the gas port holes together, your gas tube should extend into the upper receiver just over an inch. And if, if you’re sitting at that, that length gas tube, it’s going to be the correct one for the system. So we have a capture punch and for our roll pin, we just set that up in there like such.


And that’s gonna help us to set the roll pin into the gas block and gas two. So as we take a look at our parts, We have a gas port hole and a gas port hole. We wanna make sure that those line up. And as you seat it, you can take a look here and see that the, the alignment of the gas tube inside the gas block, we should be able to push that roll pin in through that hole and it would secure it.


Another thing to note, notice is that if I rotated this 180 degrees, it would still line up however. The bend and the gas tube goes towards the barrel instead of away. If you ever see this, go ahead and stop yourself. Rotate the gas tube 180 degrees and reset it. Now, the block we’re using right here just allows us to put kind of free up our hands so that we can drive this roll pin into, , into the block and secure the gas tube.


So once I’ve lined this up and I notice that this bend goes. From where the barrel is gonna mount, then I’m ready to go ahead and set this roll pin. So again, I take my roll pin and I set it right on top here, keeping downward pressure on the block, and I just give it a tap to go ahead and seat it and get it started.


Now while I’m here, I just wanted to give a double check to make sure my gas tube hasn’t moved and it should be slightly secure at this point to which I can. My large punch, set it on top of the roll pin and just give a couple of taps and that’s gonna drive that, that roll pin flush. Okay. If you could imagine not having this block, how many parts and pieces you would have to hold and clamp This block is really a lifesaver.


If you don’t have one, I would recommend it. So as we look at it, our gas tube is secure. It’s bent away from the.  and we have an assembled gas block, gas tube roll pin. Next step is going to be mounting the gas block onto the barrel and aligning it dead center with the upper receiver. Now we’re going to place our gas block gas tube onto this upper receiver group.


So I’m gonna slide this up onto, and you guys see where the gas port hole is and our gas tube is going to go through this, this port hole here in the upper receiver cor. , , upper receiver group, excuse me, at the 12 o’clock position. So as I continue to press, it should slide with ver. If it does have a little tension, that’s fine.


Actually, the tighter the better because you get a better seal, less gas leakage. So this gas tube, I’m gonna get it as close to the center of that hole as I can just, just by manual manipulation. And I’m also going to press this gas block back to the shoulder. Alright, so as we look now, we have to put the retaining.


Set screws here with, , with blue lock tight. But once I put blue lock tight in, I’m just gonna run these up and then I’m going to make a fine, , fine movement to adjust this gas tube into the center of that gas tube hole. Okay guys, once we put blue lock tight on these set screws and we’ve run ’em up, the next thing we’ll want to do again is make that manual manipulation of this gas block, making sure that it’s.


Now, some people will tell you they, they want the, the gas block offset slightly, but here in house we set the gas block all the way to the wall, and then we ensure that the gas, , the gas tube is fully floated and suspended in that upper receiver, , port hold. So if you’ll come around here and take a look, you’ll see that the gas tube is fully suspended and centered in that 12 o’clock position.


Receiver got. So from there, once we’ve centered it, we maintain control, positive control, and then we’re just going to go ahead and tighten these set screws down. Now these set screws should bind into the barrel metal. And again, we want to ensure that that thing stays center while we torque this down.


Well, it’s not really a torque down, it’s, it’s as tight as we can get it by hand.


And then we’re gonna set these and allow that blue lock tight


to set and lock those torque, , those, , set screws in place. Excuse me. So once we’ve assembled this, now we’re ready to continue on to mounting the hang guard onto receiver. Okay guys, once we’ve set this, , the set screws here for the gas block, Again, I’d like to just kind of take one more look here at the gas tube, , as it’s set to make sure it’s not leaning on one side or the other, that it is fully suspended here so that we have a true, , free float scenario between the barrel, the upper receiver, and this gas tube as it’s gonna provide our return.


So this gas tube is able to, to allow the barrel to flex and whip how it should, and we get zero, , gas. See. From the return here between the barrel and the block. So the next thing we’re gonna do, we’re gonna set on our 15 inch hand guard. We’ve already put the helo coils in. So if you guys, , purchase a, , builder’s kit from us, it will come with a hand guard, the upper receiver, the lower receiver grip, your barrel nut, all of the things that you need, minus the barrel, the bulk, bulk carrier group, , little things like that that you choose to use.


So when you receive this hand guard, It will already have the helicos in there. So, , you know, you, you won’t have to deal or mess with that. So once we set this, we’re gonna take this hand guard and set it up on the barrel nut. And there’s a nice, tight fit between the hand guard and the barrel nut. And again, what you wanna do is, is align this a as best you can.


Now you can also take a , scope rail or a pi tani mount and grab halfway on the rail. Halfway on the upper. And that would line it up, be it almost like a machine lining, that you could tighten those screws. And then we would place our two screws that we have here and our barrel mounting, , locator here.


That would go in between at the six o’clock position. And then we tighten them down. This little, , jut that sticks out here on this sleeve will go towards the rear. You would not mount it this way, it would not go towards the front. It would be mounted with this, , upward portion being close to the upper receiver.


And really there’s only one way to drop it in. And if you, you, you put it in the correct position, it’ll line up and then we can drop our two screws into the mounting holes and then go ahead and tighten them down. Now what we want to do is just kind of run these up. I have a five 30 seconds T handle. I’m just gonna run these down, just get ’em somewhat tight or like, almost like finger tight.


And then that will allow me to still have not enough friction that I can manipulate this hand guard slightly left, slightly right to where it is dead center located on this upper receiver group. Once I’ve done this without moving the hand guard, I just wanna kind of snug these up with my t.


And then I want to come back behind it myself and torque these. Okay. , let’s see where I can get this easier. I want to go ahead and torque these to 75 inch pounds. So if you don’t have this, I would say, you know, as you’re tightening them, don’t try to ring it out because you could strip or break it if.


, too crazy with it, but we’ve tightened these down to 90, , 95 inch pounds and it was still fine. So, , but 75 inch pounds is what we would tell you to mount these things at. So that’s what we’re gonna go ahead and mount this, these particular screws. And again, almost like putting a tire on, you want to kind of go back and forth because as you tighten one, the other one will.


And so I’m gonna go to about 50 inch pounds right there. And then I’m gonna come back to my, my initial screw, set it and pull it till I get to about my 75 inch pound mark, which is about right there. Okay. And I’m gonna back off and then I’m gonna go to the, , the secondary and bring.  to the same. Now, one of the benefits of doing so is that we have both of our screws on the same torque setting, meaning that one’s not tighter than the other.


So with all the jarring around the hustle and bustle, we, we now have the two screws tensioned at the same spec. So if, if one loosens, they both have to loosen at the same time. But with that kind of,  with our, our hand guard between the, the barrel nut and our hand guard, the, it is not gonna come loose. You, we, we have a good setting and you don’t have to worry about it loosening up on you.


So anytime you’re twerking, , light screws for most objects, you wanna set them at the same torque, torque setting so that if, , friction or anything is induced on it, they, they hold together and they keep. Okay guys, the next step and final step that we’re going to do for assembly would be our muzzle device.


So our 5 56 barrels, 2 23 wild barrels, all are threaded half 28 here at the muzzle. Our M 9 0 5 Talend muzzle break is also threaded half 28. So if you guys buy a builder’s kit from us, or you purchase the M 9 0 5 muzzle break, that’s what they’re threaded for. So here we’re gonna walk through the. The mounting of the M 9 0 5 muzzle break.


So as you get, , you open your box for the brake or the builder’s kit, you’re going to have a shim kit, the brake, there will be a set of earplugs and some instructions. So here we’re gonna talk about the, the mounting of this brake, how we do it in house. So the steps for this, we’re gonna run it all the way up on the barrel and we’re gonna go as far as we can go and then back it off till we get.


US arms logo to the 12 o’clock position as as seen right here. Okay, so we’re running all the way up and then we use that gap. We check with our shims. We grab a few at a time and see we, we set the shims until we can’t fit the prescribed nber of shims, whether it’s three or four, we check, and once we get to a point where we can’t set the shims in between the face of the barrel and the back of the M 9 0 5.


Now we have pretty close to the prescribed amount of shims to set the distance between the face of the barrel and our brake. Now what this does is this creates a solid flat alignment because of the brake’s length. We want to ensure that the, the brake bore line and the bore of the barrel are directly in line with one another, and that we do not have an off-centered thread because that would put us in a position of possibly having a.


It’s not a baffle, but a, a strike of the bullet inside of this mechanical, , brake, , this mechanical device, which is a brake. So we use the shims, which are perfectly ground, flat to be the, the, the kind of intercessor between the face of the barrel, which is cut flat, and then the back of this brake, which is flat, which gives us a true, , bore line from exiting the muzzle to exiting the brake.


So the first thing we’re gonna do is go ahead and thread this, this break all the way on as far as we can take it. And then we are going to set up. Now, you might get a little bit of resistance as you go up. Sometimes that’s the phosphate finish in the break. And so as we run it up, we’ll just kind of work it on and then continue all the.


Until we get as far as we can go with hand tight, you may have to work it back and forth a little bit. It is a tight fit. So once we get it on there, then we’re going to set the prescribed amount of shims. Alright guys, so I’ve run this, , M 9 0 5 breakup as far as I can get it by hand. And I have, as you can see here, a small gap between the back of the brake and the facing side of the.


So with our shim kit, I’ve opened this up with the blade and I’m going to just take a few shims. I’m taking a look at what about what I need. Just grab a few, and again, we’re just taking a swag here and I set that down. So I need a few more shims to get this closed up. That’s about right there. And the, the key here is to get or use as.


shims is possible now. They’re gonna just, they’re, they’ll, they’ll differ a little bit here and there, depending on, , where the thread was started on the barrel and where the thread was started on the break. Okay. So they’ll, they’ll be different from, you know, barrel to barrel, break to break. But again, we just wanna take and use as few shims as possible and it’ll be right before, so I can drop that in there about right there.


And then as we can. . , it just does fit in between the gap. If you don’t have to use this, this is our biggest one. I would not recommend using it. So now I have about what I need here and I’m just gonna thread this back off and then place those shims back on it and run it back up. Now again, if we take a look here from the front, this is about from the 12 o’clock position.


This is about where we want to be. Okay? That slight 15 degree camp, 20 degree. Of what we should be end up tightening with, , like an adjustable wrench or, , some other, , tool. All right guys, the final step. So we have estimated what we needed for shims between the barrel and the back of the M 9 0 5 brake.


So we put that prescribed nber of shims and then we run the brake back up to as tight as we could get it with our hands. So again, we have about a 20 degree. From the true three to nine o’clock position that we need for this upper receiver. So this brake being flat, we want the, the, the vectoring sides of the brake to be at the true three and nine o’clock position.


So what I’m gonna do is some of the paper from the shim kit, I took my blade and cut some of this, , paper off so that I wouldn’t mar or mess up the finish on the brake. And now I can use an adjustable. Here, just kind of snug it up and by eye you can center yourself in front of the upper receiver. And then this center line, as you look at it on the, in the center of the brake, you can use that to, to look right down the barrel and line it up at the 12 o’clock position.


So from here we apply a little bit of pressure to get those shims tight between the brake and the.  And when we get close you can just take a look at it by I, so it needs to go just a little bit more. And this isn’t rocket science and we’re putting a good amount of pressure between the brake and the upper receiver.


And so for here, we’re gonna turn it just about a 16th of a turn. There we go. Alright. And again, if you have a perfectly flat surface, you can take a level and set it on your upper receiver and then another line level and set it on the brake and that’ll give you like a, A no bs. This brake is level and at the three and the perfect three and nine position for the upper receiver group.


The last thing we want to do here to finish up the mounting of the brake are these two set screws here on the side. , we’re going to remove those screws and put blue lock tight on those screws and then run ’em back down. So this is gonna finish off, not only did we get a little bit of torque between the brake and the barrel, but now we’re going to cinch it down because we don’t want to produce a whole lot of torque.


But this, this clamping section of the break, we want to, , have these screws set and lock. Now this is going to be around 30 inch. For these two screws here, 30 to 35 inch pounds, you’re not gonna go wrong. And then allow that blue lock tight to set in place. And once you’ve done so the last thing we’re going to do is pull this upper receiver group off.


We can lay it at the 12 o’clock position. Now if you guys hear that, that, that rattling noise that is the floated, , gas tube kind of pinging around in that upper receiver.  right there. And that also lets us know that we assembled the gas, , gas return system, gas block and gas tube here on the upper receiver properly.


Because if it was laying against one of the sides, it wouldn’t be able to freely rattle around like that. So here we have our charging handle and our bolt, reassembled bolt carrier group where we checked the head space. So we take our charging handle in, we have to drop it into that recess there, and then slightly push.


Our bolt would make sure it extends. Now, if we want to check the gas rings on it, we should extend the bolt, be able to set it up on the table, and the bolt shouldn’t drop. If you set it in this position and it drops down like that, you need to replace those three gas rings. Okay? But so this one past the test again, if we press the firing pin here and drop the bolt, we should see the firing pin protrude just past the face.


Also, last check would be, Make sure that the firing pin, retaining pin captures the firing pin and it doesn’t fall out the back. Alright, once you’ve done those three checks, we can now set with the bolt extended and forward. Drop the bolt carrier group in. We can press our charging handle in, close the bolt, close the dust cover.


And now we have a fully assembled US arms upper receiver group with the M 9 0 5. We appreciate you guys being here with us for the full assembly of this upper receiver. We thank you again and look forward to another video. Bye.

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