I just put a pretty old Tasco World Class 10-40x60 scope on my AR. I know this is an older optic, back when Tasco made high level scopes, so I cannot find any information on it. My dilemna is as follows. At one hundred yards, I focus the scope in using the distance turret, and once I get everything set, it shows 20 yards. If I even attempt to look at anything closer than one hundred yards, everything gets blurry and cannot be focused what so ever. I would like to be able to shoot at least as close as 50 yards on occasion. Is there something wrong with the scope itself? Is something out of adjustment and needs to be repaired?