Model 1 sales 9mm upper, new frontier 4.5" barrel, aero precision midlength rail.

Using one barrel nut shim allows the barrel nut to line up properly with a decent amount of torque.

When I install the rail it comes out not perfectly straight to the picatinny rail on the upper. We are talking like 1/32nd of an inch off... Maybe less. Removed and retorqued barrel nut several times. I cant get it to line up perfectly. Anyone know any tricks?

Built an RRA upper , tros barrel and aero handguard last week. Lined up perfectly first try.

That would seem to imply that the rail or its bushing or barrel nut, are off.

Would you be concerned about it or just live with it?

On the aero handguards you have to file down. a small portion off the back end for the handguard to mate up to the upper receiver. I doubt aero would take them back because of this.

Tough question - how much of what you're doing was predicated on your ability to make the parts fit on your own initiative?

If you bought it as a finished, consumer end-user solution, I'd expect customer service to make it right, or at least point you to a smith capable of doing so, or offer a refund, unless your initial sales declaration was that you could do this without assistance.

If you bought it as "experimental" or "iffy", then it's up to you and/or your guys to make it work for your platform, including custom shims or alternative upper lapping.

I've bought experimental systems, where the final fitting of parts and pieces was up to me and my ingenuity, meaning source-local site alterations are OK for individual installations, and not the responsibility of the system originator. Commercial offerings differ in that remedial regard.

I've done a lot of prototype testing and fixing. With some thought most any error can be corrected.
Not saying it's a great situation but it's easier to tell the company that there was a problem than
to send it back and expect them to correct the part. Things are not always what they should be.
We live in a far from Perfect World.

Dave