Yesterday I "inherited" a Remington 700, 20" barrel, has "tactical" printed on side, Timney trigger, Leupold VX-R 4-12x40 scope, all wrapped in a HS Precision stock. I don't know what model Remington (700 LTR maybe?). A few questions: 1) what is this rifle capable of vis-a-vis distance/yardage? 2) How do I know what twist is on the barrel? 3) should I sell or trade the scope for one with mil dots if I want to get into 500+ yards precision shooting?