Shouldn't an AR upper be able to "pivot" down?

[marklbucla]

I just picked up two new lowers today- an Anvil Arms and a Spike's Tactical. After assembly, I noticed that neither of my uppers would "swing down" onto the lower when the front pivot pin was attached. The rear of the bolt carrier was sticking out by a hair, enough to prevent me from closing the upper on top of the lower. I could still assemble the upper on top of the lower if I slide it on and push both the pivot and the take down pins at the same time.

I haven't had a problem with this before on an Olympic, DPMS, Stag, or CMMG lower. Considering how the California OLLs were meant to be used before bullet buttons came about, would these new lowers be considered out of spec?

 

[MT GUNNY]

where exactly are the two halfs meeting?

 

[MMcfpd]

The bolt carrier should slide into the upper far enough to clear the back of the lower, so, yes, the upper should be able to pivot down. Do you have other ARs you could try these bolt carriers in? It seems odd that you should experience two of these at once.

 

[marklbucla]

You know, I was about to take a picture of it, and funny thing...guns seem to know when they're in trouble!

I guess they both needed a little bit more time to get adjusted to the parts and used to the uppers. All seems to be well now, I guess!