Brownells added pre-order for shorter barrel version of their upcoming BRN-180 called BRN-180S. It has 10.5 inch long barrel instead of 16 inch.
It is available for pre-order at
https://www.brownells.com/rifle-parts/receiver-parts/receivers/upper-receivers/brn-180s-ar-15-complete-upper-receiver-assembly-prod127762.aspxPrice: $799