I don't have any experience in building rifles, and I am now building one from some parts gathered on the EE and some others bought online. It's a basic 16" AR in 5.56. The last of the parts should be here tomorrow, so I might try assembling the thing this weekend. Here are the issues I have identified that I could use advice on:

1) I bought the upper with a barrel already installed (used but zero wear). I would like to confirm it was done correctly. What should I look for?

2) Is there any procedure for checking the BCG for good fitment? I bought a new Toolcraft one on advice I got here.

3) The barrel is weird and has an Aero adjustable gas block. It looks like the guy chose that for clearance purposes. Aero's website doesn't give a lot of info. I want to check its installation (it looks off-center) and figure out where to set the adjustment. I won't be using a suppressor or anything exotic.


This is probably going to be the 'trunk gun' if it turns out to be reliable. Until then, it's going to be a tester.

Pics of gas block and barrel? Honestly, I would just shoot it. Unless something is visibly broken or damaged, there’s not much to be worried about. For the gas block setting, you’ll just have to tune it.

Don't have one yet, and I'm at work now, so I can't get one. I'll do that later when I get home.

1.  You can either (a) shoot it, (b) set a torque wrench for the minimum torque value of the specific barrel nut on the upper and confirm it was tightened to the minimum torque value,  or (c) remove the barrel nut, inspect the threads and reinstall with the proper torque values.

2.  Lube the rails and slide the BCG in and make sure it moves freely. ETA:  make sure you have a charging handle installed when putting in the BCG

3.  Similar to #1, shoot it or remove and reinstall.  If it is secured to the barrel with set screws, I'd check to make sure some kind of thread locker (I use red loctite) was used.

This pic was harder to get than I thought it would be.

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Might still run, but my OC would have me remove, verify the GP is drilled in the 12 o'clock position and reinstall correctly.

What brand barrel?

#1 You'll need a torque wrench the the correct barrel nut wrench to check for proper torque.
    Take off the handguard, pull off that crooked ass gas block and if it isn't dimpled, get a dimpling jig here.  Or similar.
    I generally just dimple the barrel for the rear screw and use red loctite to secure the set screws, done.
#2 If you bought a Toolcraft BCG, you should be good to go.
    But you'll still want to make sure the gas tube is lined up with the carrier key when sliding it into the upper.
    It should slide into place very freely and not bind or bump the tube at all.
#3 For setting the adjustable gas block for correct gassing, just load a magazine with one round and fire a shot.
    Keep closing the gas screw on the gas block until the bolt doesn't lock open on the last round.
    Then open the screw up two clicks if it's a detent type and you should be good with a large variety of ammo.
Hope this helps out!

Yeah, that's where I am. Every time I look at it, it makes my dick itch.

Faxon - I did some looking around, and they seem to be good quality for a budget brand. This one is weird, but I got it cheap, sooo...



Thank you!

At first I didn't understand why it was adjustable, but after looking closely, I see that most blocks wouldn't go on this barrel (it has an 'integrated' flash hider).

IF you pull the barrel, check to see if the "face" of the receiver (the place where the barrel shoulder locates) has been "trued" to the receiver's bore centerline. That ensures there's not gonna' be any barrel movement once snugged up to spec.
Jon

If it's their 14.5 with integral flash hider that measures out to over16", the flash hider should be slim enough to slip a gas block over. The adjustments have nothing to do with that. It just allows you to dial your gas down to suit your ammo and set up. For now, id just leave it set up the way it is, then just dial the block back (with your weekest ammo you intend to use). Once it fails to lock back on the last round (do it one round at a time) , turn it up a bit. That'll get you running. If you want to fine tune things later you can go to a different spring and buffer and adjust accordingly.

That's a bit beyond the scope of what OP is dealing with. Not saying its a bad practice, but well outside of his current neeeds

I see - that makes sense. I was just speculating, because I couldn't think of why a person would put an adjustable gas block on a basic AR. Maybe it's just what the guy had lying around.


I just use bulk 55 or 62gr ammo, so I shouldn't need to make adjustments after getting it set up.

Check to make sure the barrel's feedramps are aligned with the upper's M4 cutouts. Any deviation can cause feeding issues. Take a wooden pick, pretend it's a cartridge trying to feed, and see if it hangs up anywhere where there's any misalignment, if any.

Any updates about the clocked gas block?

Thanks. That's the sort of tip I was looking for. I'll do that, for sure.

I haven't had a chance to fiddle with it yet. Work has been hectic lately, and I'm leaving for vacation in a few days, so it may be a month or more before I get back to this.

The budget being tight now, one of my goals was to have a light, functional rifle that wasn't expensive. As long as there aren't any issues, I've achieved that. Complete rifle with a sling and optic is under $500 at this point, and I didn't even have to buy junk parts- just shopped sales and secondhand stuff.

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I do not like the MOE pistol grip, but it was included in the kit I got on sale from PSA. I'll probably replace it with a rubber Hogue model like my other AR has. That might put me over $500 on this, but it's still quite a bargain all told.

I woke up earlier than usual today, so I decided I had time to go to the range. I took this along to test it as-is.

It didn't cycle completely, even with the gas block adjusted all the way open, so I guess there is an issue. It ejected empties, but didn't load the next round or lock open on an empty mag.

that muzzle brake looks LOUD as hell

if the gas block is installed crooked, it can partially block the gas flow

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Definitely re-install that crooked gas block. The carbon ring should be quite telling.

All you need is a set of Allen keys. Remove the handguard, back-out the set screws from the gas block, but not all the way, then center the gas block, then retighten the set screws. Don't over tighten them, and use a loctite if your comfortable.

If the former owner used loctite, you can try destroying the loctite with localized heat, then letting it cool some before unloosening the gas block set screws.

You'll know when the block is aligned.