I came across a stripped 180B upper some time back and I am using this upper to correct some of the mistakes I made with my first build.
I came across a cheap HBAR barrel and I knew then that I had to build another SBR upper.
I stripped the extension and screwed it into my upper and made sure headspace was going to be ok. Then stripped the front sight base and cut it off behind the gas port with my porta band.
Put it in the steady rest and faced it then used the live center and started the profile. I wanted to emulate what I thought Armalite would have done if they made a 180B pistol/SBR.
Here it is between my first SBR upper and a full size AR-180B
And the main reason for the changes. I came across an original AR-18S lower hand guard and discovered that my reverse engineered from pictures barrel was too short.
Still needs some stuff to finish it up but I hope to make some more progress next week when I get back to town.