I have bought most of my rifles from one gunshop because the people there typically know what they are talking about. I just purchased a 300 Win Mag and needed a scope base to mount my Mark4. I asked the guy helping me if they had any one piece mounts with at least 20 MOA built in and he quickly replied "why do you want a one piece base?" I then asked again if they had any and he said no but that they did have some Nightforce 2 piece bases with 20 MOA. My question is, most of the long range built rifles I see on this site have one piece bases...is there a specific reason for that?