u/Candid_Yam3240

Building an AR-10

Picked up a Centurion Arms MK11 16in.

Inspecting the barrel prior to install I noted a dark spot near the threads. Ran a bore snake through multiple times, nothing came out. Same dark spot.

Sent the barrel to centurion arms, they said they found nothing and are shipping it back to me. Great customer service experience.

I’ve built countless rifles in my life, this is the first time I’ve ever seen a barrel like this. Has anyone seen something like this on a brand new barrel before?

I trust the manufacturer, however this just feels strange.