We put a 3-9x40 prostaff nikon on a 270 a couple years back when my wife's dad gave it to her because it had to much recoil for him. Using a muzzle brake.....yes a muzzle brake on a 270......she took a big cow elk at 392yrds that year with a well placed single shot. The father inlaw borrowed it back to shoot a cow elk this year with a decent single shot at 377yrds. Conclusion: No problem with the BDC reticle for vital zone hits, Nikon makes a good scope for the money, 270 can easily do elk with solid shot placement. I know people who have done six hundred yards on elk with the 270, I like more gun but it can be done. The reticle should give drops out to 6ish. My 300wsm still wares a 4-12x40 prostaff nikon bdc, I can't find any excuse to change it because it works good............................................................... For DEAR.......SORRY for elk rambling...........With practice as far as you can group them in vital size targets 600 should be no problem from a 100yrd zero but after that you have to mess with turning the magnification down and that is a bit tricky to do exactly the same every time. Can be done, check out Nikon's "spot on" online ballistics program if you have not already.
It depends. If it is a buckmaster or monarch: probably but test it for repeatability. If it is a prostaff I would stick to the reticle. I love Nikons and there bdc but even with my monarchs: I have not tried to dial in shots. Might work great and might not? I use the bushnell elite tactical scopes for designated long range dialing and the nikons for sub 700 yard traditional hunting rigs.
To many varaibles to correct for past 500M with that type of BDC. The lack of holds for wind values make it to risky, not to mention the shape of the aming points. If we were talking a Horus system thats another story.
Im sure guys do it all the time but imo its just not enough precsion.