I have a leupold B&C and a swarovski TDS......the swarovski crosshairs work at any magnifcation, the leupold only work at max magnification, which is fine because those additional crosshairs are at 300,400,500yds....and really at that range.....I'll be at max magnifcation, though it is ncie that the swarovski works at any mag.....though at 2 or 3power those crosshairs are tiny.

Also the leupold has 2 settings to work with differen calibers, so kinda like at full mag for a certain category and at like just undre full mag another category.

The scope/booklet should explain it quite well, but im assuming the BDC reticle probably only works at full magnification? though if for a muzzleloader with max range of 250yds im not sure.....how that would work.....

Most calibers will work....you just have to find the right bullet setup.....so sometimes you end up wanting a bullet with more drop.....vs.... a flatter shooting one, if it matchest your mult crosshairs better.

My swaro TDS kinda requires me to shoot 225gr vs. 250gr, though 250 will work wll, the 225 are dead on the money!

I'm quite sure you can find a load to work with the scope and the .243wssm