Upper Receiver Important?

[jcaz76]

Hey guys,
Question... I am in the process of building an AR15. After plenty of research, I understand that the BCG, barrel, and FCG are the most important aspects when it comes to accuracy. What about the upper receiver? Is it safe to say that if it is milspec, it will perform equal to a more expensive milspec?

[alpha_romeo_XV]

Do you want an A2 (carry handle) or A3 (rail) or slick side (no port cover or forward assist)?
Make sure to match the upper feed ramp profile to the barrel extension profile ( M4 feed ramps or standard).

[jcaz76]

I want an A3 for sure. I will be sure to make sure that the profiles match.

[Junkie]

It's not particularly important, but can cause problems if too far out of spec.

What's the purpose of the rifle you're building? I like the Aero Precision M4E1 upper because it has a rock solid handguard and better barrel nut.

[m850168]

Generally, yes.

Exceptions for true monlithic uppers, which will provide superior accuracy for sighting systems mounted on the handguard portion - but for most of us, that means superior accuracy with BUIS at significant cost. And, a well-mounted free float handguard does pretty well.

[jcaz76]

It will serve a few purposes. First, a marksman rifle. I LOVE having a highly accurate rifle. Second, coyotes, foxes, and bobcats. I love hunting

[jcaz76]

This is the upper I am looking at:
Link...

[Junkie]

http://www.schuylerarmsco.com/produc...uard-combo-993 that's what I'd suggest.

[jcaz76]

Hmm, my barrel is an 18" rifle length. I don't see one with the rifle length handguard... :/ only the extended rifle length one...

[Junkie]

Are you trying to run a standard FSB or something? I run a 15" handguard on an 18" rifle gassed barrel with no issues.

[jcaz76]

Oh, I though that rifle length typically use 12" hand guards? I may be mistaken.

[Junkie]

I believe a rifle length handguard will leave the gas block exposed with a rifle length gas system (so that an A2 FSB won't interfere with it). Most ARs I see with free float handguards have handguards longer than the gas system.

[LeadFarmer74]

Hmm, my barrel is an 18" rifle length. I don't see one with the rifle length handguard... :/ only the extended rifle length one...

What has block are you using? What type of handguard as well.

Are you trying to run a standard FSB or something? I run a 15" handguard on an 18" rifle gassed barrel with no issues.

This a the setup I just built out of a mega arms 18" and geisselle 15" rail.

[Sicarius]

I personally like vltor upper receivers. I believe that a billet upper will be stronger, more exact to measurements and have less of a chance in having flaws in metallurgy. That said, I have no problem using a standard cast upper from a quality brand... especially considering the cost difference.
Kevin

[Junkie]

Sicarius, standard lowers are forged rather than cast. For the same material, forgings are typically stronger than billet.

A raw billet is typically cast (as a shape, can be round, square, rectangular, etc) and then machined to final dimensions, so it's not as strong as a forging.

I don't know enough to say anything about dimensional tolerances.

But... I believe the Aero Precision M4E1 that I'm recommending is billet as well, because for a small production run it's cheaper to do billet than forged. I'm not saying there's anything wrong with billet. Sometimes billet items are thicker to make up for the reduction in strength.