first build

So I’m doing my first build and was inspecting the lower receiver. I noticed a orange sand like material in and around the pivot pin channel. It cleaned up with a cleaning cloth. I cleaned inside the channel further with a toothpick and there was more orange and black debris in the channel...

In my research for my first AR build, I have seen people preparing their lowers by running drill bits (by hand) through the detent and pin holes. I totally understand the need to inspect for burrs, machining chips or finish build up and addressing issues if something is noticed. Doing it to...

So I’m planning out my first build and have done a ton of research on setups and components. From a high-level, I’m considering .... - 16” 556 mid length barrel (probably Aero Precision complete upper) - Carbine stock - Two stage trigger (LaRue) Any big picture thoughts ... 1. 16” Carbine...