A thought... Ideally, both eyes open is the best firing situation. It keeps your field of vision at its widest. But seriously, if you are firing your gun at a BG, your focus is on the COM of that BG. If they intend to hurt you, you should focus on them, "neutralize" the target, and then assess the situation from there. If you are more comfortable/accurate with one eye, what is wrong with using one eye? Does closing one eye, firing twice, and then re-opening the eye take that long?