Posted by Yukon58 on 1st May 2023 I chose to go with this particular sixteen” upper for my Colt lower after the fiasco While using the atf pistol brace ruling. I wasn’t about to fluff all-around so I went all Colt and am glad I did. The Colt SMG fires https://colt-smg-upper51627.blogmazing.com/26351935/what-does-colt-smg-upper-mean