My C-2 had a Lightning Link set up in a Bushmaster, He milled a little bit off the inside edge of the carrier to make it fit in, the way a LL works is sort of Un-Natural when you think about it so a little custom fitting is to be expected. They do work fairly well with the Buhmaster Upper and a Colt Carrier, and thinking about it he rans his LL in my Bushy once and it ran without any problem
Guess it must vary on when the Bushy was made but not sure on that point. I passed up buying it though as I did not like the price of it or that it was not select Fire, Bought my AC556 instead to keep my Uzi Bolt gun company
They will also fit in a Model 1 Upper with a Colt Carrier in them without modifacation.