This Colt AR-15/M-16 roll die sold on Ebay on 13 May 2020 for $1,302.77. The photos below are from the auction listing.
AR-15 Property U.S. Government Roll Die
The Colt AR-15 Resource
"A site dedicated to the history of the Colt AR-15 rifles, carbines and associated items"
The Colt AR-15 Resource 