Hi guys, I recently built a mid-long range ar15. Looking to get a trijicon accupoint 2.5-10, green mil-dot retical. Anyone on here know the diference between a 221 and 222 as far as model number goes? Also, I have a acog, love it, but don't know much about the accupoint besides its in my price range, feel free to weigh in with opinions if you own one allready. Thanks