7 feet is what i practice for hd. and as far as being able to hit 21 feet so you can hit closer that is totally the opposite. It is harder the closer you are believe me and if you are ever in that sittuation you will understand. it is hard to explain but in my experiences closer is harder well when you are shooting at humans that shoot back instead of a paper target.
Sic Vis Pacem, Para Bellum
I will Never Forget 16 Aug 2004, Sadr city Iraq