I have an older probably late 70's Remington 700 ADL in 7mm mag. I have shot a few deer with it an planning on taking it out west in 2020 on an Elk hunt. I am starting out from scratch now and using some different factory ammo. I am also using either a Monarch 3 or Vortex viper scope to start with. I may switch to a Leupold LR precision or VX-5 since I can get a deal on them. I am also going to switch to BDL detachable magazine. Which one should I get ? I am also going with a Timney trigger. Now if I need or want to switch barrels,how do I decide which one to get ? been watching different threads on here and most seem to have their barrel picked out without any difficulty. Thanks