I assume you found this thread by using the search button. That's good. Now go to the top of this page and hit the tab that will bring you to page one and read the first post and check out the photos.
I am looking at mine now. It is an old Colt SP1 upper and a BCM 11.5" bbl.
https://www.m4carbine.net/picture.ph...pictureid=1897