Receiver rail lower than Troy Alpha rail EDIT- SOLVED

[glen]

So I just finished a build mating an unbranded A3 upper with a Troy Alpha rail.

Upper receiver rail is a hair lower than handguard rail.

I believe its the upper that's out of spec as I tried the rail on a Spike's upper and it lined up ok.

Also a Larue mount swapped between the two required adjusting the tension as it was loose on it.

It looks to be straight otherwise, and everything else about it seems to be ok. Barrel fit fine, bolt and charging handle go in with no issue, fits fine on a Colt lower.

That kind of got my attention because till now I was fine with generic uppers.

Other than cosmetics and maybe a bit more trouble zeroing, what other things do I need to watch out for with generic uppers?

Can these generic uppers have other issues or be any danger to build on?

[Onyx Z]

I stay away from generic parts in general for this very reason. If a part is out of spec, I attribute it to poor QC, which could very well translate to safety issues. Parts are not parts like many are led to believe.

[Iraqgunz]

Where did you buy the upper? Has is occurred to you to return it and tell them it is out of spec and explain why?

[PaLEOjd]

Don't go cheap when it comes to rifle parts. Paying a little extra for well known quality parts will save you a lot of headaches in the future.

[glen]

IG, I got the upper as part of a swap deal with someone sometime ago, not at a retail outlet.

Agreed with everyone's points. Nowadays I generally stay away from generic, but I was under the (mistaken?) notion that as long as it came from a US forge (AH, Cerro, etc) an upper would be ok.

Thinking about it some, would it be safe to assume that since this upper started out as a US Cerro forging, it is ok structurally?

[Iraqgunz]

The forging has nothing to do with the finished product. Out of spec lowers and uppers happen quite a bit.


IG, I got the upper as part of a swap deal with someone sometime ago, not at a retail outlet.

Agreed with everyone's points. Nowadays I generally stay away from generic, but I was under the (mistaken?) notion that as long as it came from a US forge (AH, Cerro, etc) an upper would be ok.

Thinking about it some, would it be safe to assume that since this upper started out as a US Cerro forging, it is ok structurally?

[BBossman]

A quality forging doesn't mean quality machining. Look at the picture below, plenty of chances to make mistakes.


http://i444.photobucket.com/albums/qq169/bbossman1/upper-forgings_zpsf906fd71.jpg

[glen]

^ I agree. Looks like I got one with an out of spec rail but since everything else fitted fine I assume it's safe to use?

I earmarked a Bobro for this build so no adjusting needed to fit to rail.

[glen]

So the Troy rail sat a tiny bit higher than the receiver rail.

Thinking about the mounting system of this particular rail, it dawned on me.

The minimum height of the rail is dictated by the barrel nut teeth tips, as this is where the rail rests on when in place before the clamps affix it in final position.

I had used an older barrel nut with this build and I remember some burrs on the teeth tips where the wrench slipped a few times.

So I removed the rail, de-burred the barrel nut teeth tips, then test-fitted. The rails now sat level!

Cleaned the area of filed metal, cold blued the barrel nut teeth tips, and installed the rail. Aligned with a carry handle and snugged it up. It's all good now!