I've got a old 11-87 in greenleaf that i bought in 95. It is also th SPTurkey. I will start by saying that i love this little short barrel gun. Mounted a FastFire last year. I used the B-Square mount and on my gun and there is just enough room on the mount below the dot to see the Gobble Dots. After using it on several hunts last year i would have to say that seeing the old sights will never be a issue. No complaints whatso ever with the FastFire.... Great sighting system, wish i had one of the Bird protectors tho, they were sold on Old Gobbler for awhile and may still be, Good luck and hope this helps make your decision