That piece brass of looked like shit from what I could see in the pic, I think you need sort your brass & scrap any that looks like that piece. You did not say why it stuck.
The barrel was wrapped up by dpms with sticker an bar code on it. With it wrapped up you could not tell it was not fluted, there for it is on dpms. can you not read
If you are going to make it a single shot the only thing you will need is the larger bolt face
If it's a repeater the OACL is going to be a problem in the mag area