I have a 300 wby mrk v (southgate) with a 24" barrel,topped with a leupold VXIII 4.5x14x50 LR. (I will add turrets later). I reload 180 gr nosler partitions and know the gun well and am confident out to 400 yrds. I am wanting a 400-800 yrd ++ gun for elk and mulies. What do i need to do to get that out of my gun?(longer barrel,gunsmith,stock?). Or would i be better off getting something made. I do pack my gun so I would like to keep the weight between 10-13 lbs. Any info would be of great help.