Thanks to everyone of you. very helpful here.... :-X

now one last one before I go shopping : my rifle is a 300wsm, my scope has a total of 60 Moa. if I get a 20 Moa base, that means I still ca go down 10 Moa and 50 Moa up at 100yards. is there a downside for using a 20Moa base on my rifle to be sighted at 100 yards? I mean why not buying a base with more distance to it ...? and the second hand market is probably better for 20Moa tactical bases, right..

what is the catch? please educate me ;D