Building my first Ar-15 Upper today. Check list?

D

D 23

BANNED
BANNED
BANNED
EE Expired
Rating - 100%
4   0   0
Location
705
Yesterday I got the last part I was waiting for so now I'm on to the build.

I know it's fairly straight forward but I'd just like to tap the experts here in case I'm missing something or there is a better way to do this... it is my first assembly.

Parts:

UR with FA and EP cover (already assembled)
Cocking handle
URX 3.1 handguard and panels
Barrel
Barrel nut
Compensator with timing washers
Gas block
Gas tube
BCG complete
Optics (haven't decided on them yet)


Tools:
Vice bolted to workbench
Magazine block (plastic block to hold lower)
UR vice block (hinge type)
Gas tube guide (came with UR block)
KAC barrel nut wrench
Allan key for gas block
Copper anti seize for barrel nut threads
ft/lbs and inch/lbs torque wrenches


I'm going to clean the parts completely before I assemble them. I'm going to torque the barrel nut the first time to 30 ft/lbs, let it off, torque it to 35 ft/lbs, let it off and then torque it to whatever times the gas tube after 35 ft/lbs and no more than 80 ft/lbs. I will add a thin coat of copper A/S both thread surfaces before I start.

I'm going to fit the gas tube to the gas block and test it for air flow then slide it into place and torque the one allen head set screw into it's groove and the other against the barrel. I'm not going to drill and pin it.

Assemble the rest of the UR (check headspace) and take it to the range for a test fire.

Questions?

Did I miss anything?











Lastly, I have both an aluminum and steel barrel nut (KAC). The steel one came from the guy who made me the barrel nut wrench and the Alu one is what came with the handguard. Which is better to use?
 
Last edited:
Soon to be at the same stage; have read elsewhere to use a mil-spec extreme pressure grease such as Aeroshell 33MS instead of a copper based anti-seize product.

P.S. "go no-go" gauges to check headspace.
 
Last edited:
Watched the videos to put together my list. It's basically down to a few questions specific to my parts maybe.

I forgot to add checking headspace but it was on the list. thanks.

I was unable to find aeroshell or other aerospace or marine grease rated higher than 1800 but I'm not worried.


I have the other torque specs now too.

Edit:

I found all the answers to the questions in my first post. I got a URX specific install that had more info that the first video I found and answered my fitment question.

Got everything but the steel vs. alu nut question sorted.
 
Last edited:
D 23 said:
Watched the videos to put together my list. It's basically down to a few questions specific to my parts maybe.

I forgot to add checking headspace but it was on the list. thanks.

I was unable to find aeroshell or other aerospace or marine grease rated higher than 1800 but I'm not worried....
Click to expand...

If you use quality components, ie barrel and bolt, you don't need go-nogo gauges. Also, any high pressure synthetic grease will do on the barrel nut threads. Good luck with your build.
 
All done.

That was a lot easier than I thought it would be to tell the truth.

The KAC rail bottom drops off so it's really easy to manipulate the gas block and you can install the barrel nut with the gas tube in place as it doesn't interfere with turning the nut.

The only issue was keeping the rail on the hand guard lined up with the rail on the UR when torquing but I just clamped them together with vice grips (thumb tight)...

**Image and video linking functions will be enabled after you have contributed more to the forum**

And my upper is almost complete. Just needs optics. I'm going to go down to Epps to see what they have.

**Image and video linking functions will be enabled after you have contributed more to the forum**

Still waiting for the lower I ordered so I can build that up but I have a Spikes/Magpul lower to put on for now so I can get some break in rounds through it.
 
D 23 said:
All done.

That was a lot easier than I thought it would be to tell the truth.

The KAC rail bottom drops off so it's really easy to manipulate the gas block and you can install the barrel nut with the gas tube in place as it doesn't interfere with turning the nut.

The only issue was keeping the rail on the hand guard lined up with the rail on the UR when torquing but I just clamped them together with vice grips (thumb tight)...



And my upper is almost complete. Just needs optics. I'm going to go down to Epps to see what they have.



Still waiting for the lower I ordered so I can build that up but I have a Spikes/Magpul lower to put on for now so I can get some break in rounds through it.
Click to expand...

Good work, shoot it well! Had I seen this thread earlier I could have shipped you a small tub of aero shell grease. I bought a big tube and now have a multi lifetime supply.
 
A Geissele reaction rod is a much better tool to use when tightening the barrel nut. No torque is transmitted to the receiver when using one.
I've never checked for headspace, if you use quality parts and the bolt cams into the extension with a cartridge in there it good. If I was assembling a bolt action where headspace was adjustable it would be a different story but for an AR it isn't required as long as you don't use a Norinco barrel or receiver.
Rifle looks good, well done. Now we just need a range report :)
 
cr5 said:
A Geissele reaction rod is a much better tool to use when tightening the barrel nut. No torque is transmitted to the receiver when using one.
I've never checked for headspace, if you use quality parts and the bolt cams into the extension with a cartridge in there it good. If I was assembling a bolt action where headspace was adjustable it would be a different story but for an AR it isn't required as long as you don't use a Norinco barrel or receiver.
Rifle looks good, well done. Now we just need a range report :)
Click to expand...

I have installed URX more time than I should. They are not fun!

The URX needs to have both the upper and the rail lined up and clamped down by a rail fixture to fix in place, while the barrel nut is torque down. The reaction rod does not work with the URX installation. The rail will will be rotating if it is not clamped down.

The proper fixture lined up the upper and the rail, and also serves as the clamping block. The way to think of it, the rail itself is "half of the barrel nut", the barrel nut is just a cap. That's why URX 4 ditched the cap, and simply get the installer to shim the rail.

The URX installation actually calls for the use for loctite blue 242 to both the barrel extension and the barrel nut, instead of grease. There is no difference between the original URX and the 3.1, just different barrel nuts. The original URX is flat so M203 sleeve can slide in.

URX-Armorer-P3-of-3.jpg
URX-Armorer-P1-of-3.jpg
URX-Armorer-P2-of-3.jpg


2.jpg
 

Attachments

  • URX-Armorer-P3-of-3.jpg
    URX-Armorer-P3-of-3.jpg
    43.3 KB · Views: 139
  • URX-Armorer-P1-of-3.jpg
    URX-Armorer-P1-of-3.jpg
    65.2 KB · Views: 136
  • URX-Armorer-P2-of-3.jpg
    URX-Armorer-P2-of-3.jpg
    57.8 KB · Views: 137
  • 2.jpg
    2.jpg
    82.4 KB · Views: 137
cr5 said:
A Geissele reaction rod is a much better tool to use when tightening the barrel nut. No torque is transmitted to the receiver when using one.
I've never checked for headspace, if you use quality parts and the bolt cams into the extension with a cartridge in there it good. If I was assembling a bolt action where headspace was adjustable it would be a different story but for an AR it isn't required as long as you don't use a Norinco barrel or receiver.
Rifle looks good, well done. Now we just need a range report :)
Click to expand...

Was a fan now I use these.

https://selectshootingsupplies.com/products/bev-block-ar15-m4
 
cr5 said:
If I was assembling a bolt action where headspace was adjustable it would be a different story but for an AR it isn't required as long as you don't use a Norinco barrel or receiver.
Click to expand...

I used a VLTOR MUR upper with a matched, match barrel and BCG. I shouldn't have any headspace problems but I'm shooting this weekend with a guy who has the go/no go kit so I might as well check.

I don't expect any issues as it functioned as it should when I was cycling dummy rounds through it.

Didn't find the optics I wanted so for now it's either wait or put an old 3x9 Fullfield II on to see how it groups once a few rounds go down.
 
You must log in or register to reply here.
Back
Top Bottom