I never use a 100 yd zero with BDC reticles. It's usually 200, but 250-300 is feasible. As others have said, it comes down to figuring out useful values for the lower hash marks. A lot of playing with the numbers will give you the result you want. I also keep a small notation attached to my rifle just in case I run into a looong shot that I feel confident to take. So far, they have worked perfectly for me out to exactly a quarter-mile, and I'd feel comfortable stretching further if need be. I also want the freedom to "point and shoot" out to typical hunting ranges, and the thought of farting with hashmarks at 250 seems silly.
