lookin to get a new scope for my Remington XCR in 300 WSM and lookin through the Cabelas catalog got me confused I'm lookin to get a Leupold VX-III in 4.5-14x40 and they offer 3 different models 1st is 4.5-14x40 2nd is 4.5-14x40AO and 3rd is 4.5-14x40LR so whats the difference? and whats everyone recommend?Also whats better a 30MM tube or 1" tube?