Thanks CJW, shooter545 & Lastrites...
Found receipts for this build. The gas block & tube were Brownells branded parts. I don't know who makes these parts for them. AH HA... another discovery!
I found 4 boxes of Hornady 123 grain AMAX ammo in a cabinet in my work room. I'd completely forgotten I bought them 2 years ago. 
Can't get 123 AMAX ammo anymore... 
Found receipts for this build. The gas block & tube were Brownells branded parts. I don't know who makes these parts for them. AH HA... another discovery!
I found 4 boxes of Hornady 123 grain AMAX ammo in a cabinet in my work room. I'd completely forgotten I bought them 2 years ago. Can't get 123 AMAX ammo anymore...