I have been scope up on all my Turkey guns for 10 years now. I will never go back to red dots or open sights. I have killed birds running, flying, and everywhere in between.
Nikon BTR is the best out there curently:
1. 5 full inches of continuous eye relief
2. Cirlce within a circle allows you to range birds on low or high power.
3. Very ergonomical/large power ring adjustment dial
4. Solid consturction
5. PRICE--Natchez Shooter Supply $130 Cabela's $149
Good Luck