I'm looking at building an AR using an Aero precision upper. I haven't decided on a barrel yet but am thinking 18 inches. My question would be, when threading the barrel into the upper receiver, what do I need to make sure the fit is optimal? Go/no-go gauges? I've read something about o-give but don't know what that is.

Also, how do you decide what brand of barrel to use?

Thanks and if this has been covered already (which it probably has) just point me in the direction and give me a kick in the butt and I'll toddle over to that thread...

I could explain it but youtube does a much better job, search ar15 barrel install and you'll be up to speed in 10 minutes lol.

LOL, will do. Are there preferred brands for 6 ARC barrels? Or are we talking Chevy vs Ford type of discussion? I'm not wanting a heavy barrel for competition shooting but one I can haul around when walking to stands without breaking my back.

Good luck with youtube. The new thing over there is deleting gun videos for simply screwing on a suppressor. They are really hammering the gun community.

Well, our lovely governor signed a bill that's against those "evil black rifles" so I'm not sure if that means I can't even get the parts to build one now or not.

We'll see...

Do some research as you do not thread the barrel into the receiver.

I shall. Never built one myself.

No need to worry about headspace as you can't change it anyway. You slide the barrel exterior which will already be on the barrel when you receive it into the upper receiver and then thread the barrel nut on and torque it. Depending on the barrel nut style you might need to try various shims that go between the barrel nut and the barrel extension to get the barrel nut to clock or index properly so when you attach the handguard to it it will be straight. Some barrel nuts also have have to clocked so the gas tube passes through or over them properly. In other words the some have a series of holes or notched that the gas tube has to go in or through. It's pretty self explanatory.

Thx for the explanation, Varminter. Are we still able to buy uppers after the latest bill was signed?

Well.....it's all clear as mud. I don't think anyone knows what's goin on. It's state law and I'm not sure how the state can stop an out of state company from doing business or how the state could control or monitor it. I think they are gonna find themselves in a legislative bind. I look for thr courts to temporarily issue a stay on the law until it's sorted out which will open the door to biggest firearming purchasing explosion ever seen.

Only one way to find out. Click the"order" button and see what happens.

Id guess there is some clicking goin on.