I recently purchased one of the Tasco SS 10X42 scopes from S.W.F.A. Question for those who own one, too: after zeroing the scope, is there a way to turn the turrets back to "zero" like you can do with the Leupold models I've seen? I notice the allen screws around the turrets. Is that what they are for or are those to disassemble the turrets? Thanks for any help you can give me (the "manual" that came with the scope was real sparse on information).