Order of Operations for AR Build

[Srikaleak]

So I'm in the slow process of building my 6.5 Grendel SBR. I get a set of parts every month due to budget constraints. My question to you is: Is there a mandatory order-of-installation for an AR15 build?

I ask because I have a stripped upper and a lower with trigger kit already installed. I also just received a lower parts kit with the FA assembly and the Ejection Port Cover assembly arriving soon. Installing these parts should not affect the installation of the barrel+gas system or buffer+stock/bcg/charging handle area correct?

My next set of purchases will be a complete bcg+charging handle, then the barrel+gas system parts. Lastly, when my Form 1 comes back, I will be ordering the buffer tube, buffer, and stock.

Is this a good plan of attack for my first build? Or am I about to make some painful mistakes?

I have watched vids on AR builds but they have all the parts ready to go. Should I just sit on the parts and assemble the rifle once I have everything?

Thanks in advance for the advice.

 

[Tx_Aggie]

Should I just sit on the parts and assemble the rifle once I have everything?

I know the anticipation may be hard to resist, but this is probably what I would do. Or at least wait to assemble each half (upper & lower) until you have all of the parts in hand for that assembly.

For the upper, in most cases it's easiest to do the dust cover and forward assist before the barrel. The little C-clip on the dust cover is extremely easy to lose, so be sure to work in an area that it will be easy to find if it takes flight or hits the floor.

For the lower, keep in mind that you won't be able to install the (rear) take-down pin until you are installing the buffer tube assembly, as the end plate holds the take-down pin and detent in place. Otherwise, on the lower I like to start with the magazine catch, then the bolt catch, trigger guard, pivot pin, trigger, grip and selector, then finally the take-down pin and buffer tube. Others may have a different opinion about where to start first on a lower.

 

[winniedonkey]

I personally only finish a upper/lower if I have all the parts. Just seems logical. Sucks having parts stare at you. I put them away from sight. Just make sure you have all the tools necessary and good lighting. And beer.

The above order is pretty much how I do things. Good luck on your build.

 

[flyer]

NFA will be the gating issue.

I'm not sure about the rules for engraving your lower as an SBR but you probably don't want to assemble your lower until it is engraved.

You don't want to assemble your upper until you have your tax stamp and engraving to avoid constructive possession (unless you have a pistol lower or don't have a rifle lower).

The main thing is stay legal first.

 

[Srikaleak]

Engraving is already done as well as form submission and cashing of the check. I am now in the waiting game

 

[flyer]

Ok, well I think you can own the barrel but I wouldn't install it in the upper until you have your stamp unless you have a pistol lower to avoid constructive possession.

I'm not 100% certain but I think you can assemble the lower without issues.

There are things you can do with the upper before installing the barrel. You can install the FA and dust cover, they won't interfere with the rest of assembly. You can install your gas tube in the gas block (this can be a pain in the ass). There is nothing to install with the charging handle and BCG. I'm not sure what type of handguard you've got but it's generally last.

For a lower I generally do pivot pin and detent, then bolt hold open, trigger with disconnector and spring, selector and detent with grip, hammer with spring, magazine release, buffer retainer pin with spring/buffer tube with end plate, castle nut and takedown pins with detent. Trigger guard last and I try to buy lowers with integrated trigger guards so I don't have to.

The order of the lower is kind of how it has to go. There are lots of videos out there I suggest you watch a few.

The trickiest part is installing the bolt hold open roll pin and the trigger guard roll pin. The bolt hold open roll pin is a common source of scratches on lowers and the trigger guard roll pin can break a lower if you do it wrong.

 

[Srikaleak]

I appreciate the advice folks. I think I'll leave the upper alone until the Form 1 comes back and focus on completing the lower then. It shouldn't be a problem to own a complete lower (that's designated as an SBR) without an upper, right?

 

[Hippy_Steve]

I appreciate the advice folks. I think I'll leave the upper alone until the Form 1 comes back and focus on completing the lower then. It shouldn't be a problem to own a complete lower (that's designated as an SBR) without an upper, right?

just don't attach the upper to the lower until you get your stamp. Pictures with the completed upper and lower near each other without a stamp can be interpreted as constructive intent, so no social media pictures until you have your stamp.

 

[Strykervet]

Okay, here's what ATF told me. If you have another SBR AR receiver, it's not constructive possession. If you have submitted the form and don't mate the assembled upper to the assembled lower, it's not constructive possession. In fact, they once told me to not submit my Form 1 until I had the upper I wanted to use when I called about not being positive about the OAL and I didn't tell them I had other SBR's already.

In the past though, it's always been considered to be on the safe side if the upper is stored separately to the lower, and some have a friend who doesn't own the particular rifle you're assembling hold the upper until you get the stamp back.

So you can assemble your lower and upper separately as you go. There are some parts that need to be installed before others. What I'd recommend to supplement the youtube videos is the Colt or US army TM (technical manual) though having the FM is also handy, the TM will show how to completely disassemble and reassemble, in order, with all torque specs, etc. It has pictures but the older blue Colt manual has crummy pictures but still useable. The M16 or M4 manual will suffice. IMO anyone building their own AR needs one of these manuals and it's what I used when I started. I'm assuming you have all the tools but if not, the TM lists 'em.

I'm assuming you're planning on building more since you went that route, so I'd be sure to get a good barrel wrench (some suck) a set of roll pin starter punches, knurled steel punches, blue masking tape so you don't bugger up the lower, a small hammer (gunsmith hammer w/interchangeable heads or a small ball peen is what I use) clamshell upper vice block and lower magwell block, proper torque wrench (cheap bar type torque wrench is fine for this and more accurate than a cheaper adj. ratchet type!). Brownells sells all these tools in a kit and if you don't have 'em, it's a good deal IIRC. If you're only gonna build this one or two, I'd reconsider if you don't have the tools yet and have someone barrel the upper for you. Doesn't need to be a gunsmith just to barrel an upper, just a competent builder.

Tip: the blue tape on the lower and the use of the roll pin starter punches is how you install the bolt catch and other roll pins without marking up the lower. Get 'em started with the starter punch (the pin fits in the end so it doesn't slip) and finish with the appropriate steel punch. Forget the tape and you're likely to hit it with the hammer or punch and bugger it up. Forget the roll pin starter punches and it's just a lot harder.

Depending on the barrel, it could be shorter or longer than you think. The Lilja 6.5G 11.5 is actually a bit shorter, they include the barrel extension in the length (where, say, Noveske doesn't). So certain handguards won't work if they're gonna cut it close. Just a heads up, I had to send my 10.75 back for a 10" so it'd fit when I built my Grendel SBR.

Install parts according to their directions if they differ from the TM. Ask on here if you run into problems before buggering it up. Someone here will always be glad to help.

The TM and FM as well as other manuals can be downloaded from Scribd for free, you just have to sign up for the free trial and remember to cancel it within the month. Good luck!

 

[oldfatguy]

Recently used a Geissele reaction bar (fits into the barrel extension) mounted in a bench vice to torque a barrel nut. Keeps the stress from damaging the aluminum upper. And a good barrel nut wrench is very important.

OFG

 

[Tx_Aggie]

As was said above, if you have a reason to own the short barreled upper there should be no worries about constructive intent.

For this reason, some guys will build an engraved lower up as a pistol while they wait for their stamp. This allows them to shoot the firearm to function check everything and to enjoy it while they wait on the stamp. Several friends have done this with most using either a cheap pistol buffer tube or one of the nicer braces (selling the brace off after their stamp came back).

This may raise some eyebrows here, but it is also perfectly legal to build the lower up as a pistol using a carbine tube, as long as you do not attach a stock. Using something like a Thordson's buffer tube cover or even a couple of wraps of paracord or foam tube to cover the tube so that a stock isn't easily attached is a cheap way to make sure the pistol lower isn't confused with a regular rifle lower.

So, if you already own either an SBR or Pistol lower, you should have no worries about owning an additional short barreled upper.

If you do not, then it's best to either wait to assemble the upper until you have your stamp in hand, or to build a lower (either your soon to be SBR or another) up into a pistol while you wait on the stamp so that you have a reason to posses the assembled short barreled upper.

 

[Srikaleak]

This will most likely be my only AR15 so I'm trying to cut down on purchasing tools as much as possible. I'd like to do everything myself so I may just buy everything and then flip them on here or Craigslist.