Zel Custom Manufacturing added uppers chambered for the .416 Barrett to its Tactilite line-up. According to the Zel Custom website, the initial production run has already sold out, but they are taking orders for the next batch.  I would venture to guess that is the position many businesses would like to find themselves in.
The Tactilite uppers are designed to mount to any standard AR lower, and work as a bolt action gun. A Cerakote finish is standard, with optional patterns and stenciling.
Standard barrel lengths are 18.5″, 22″, 24″, and 29″. Custom lengths up to 36″ are available as special order items. The barrels are free floated, and are made by Mossberg or Lothar Walther, depending on the model.