I'm trying to decide how to sight in my IOR M2.  This is going on a patrol carbine so shooting will most likely be less than 100 yards (50 is more realistic).  I know the 50 yard zero is supposed to have minimal POI shift at 100 yards, but does that apply to every type of optic or just iron sights?  I also like the idea of the BDC on the M2 and I don't think it will work very well (should I do 100 yd + plinking) if I zero at 50.  What do you guys think?  Thanks.

I believe the BDC is calibrated if you zero at 100yrds. I zero all my optics/ iron sights at 50yds. Its good from 25-250yrds.
Since most of your shooting will be at 100yds in, I would prob not worry about the BDC and zero at 50yds.

Quoted: I believe the BDC is calibrated if you zero at 100yrds. I zero all my optics/ iron sights at 50yds. Its good from 25-250yrds. Since most of your shooting will be at 100yds in, I would prob not worry about the BDC and zero at 50yds.

+1

The 5.56mm round is most effective within 250 yards anyhow.

OK.  Thanks guys!