I am a relative newbie to long range hunting and this forum. After 30 plus years with my great 30-06, I am going to build a 300 rum. I want to have 2 scopes, VX7 2.5-10 for most hunting and a vx7 4.5-18 for a back up and for long range Elk when I feel I am good enough. My questions are do the detachable systems hold zero properly, and which is best? Thanks for any help you can give me.