BUIS Zero Change!

I stumbled upon something a few years ago when zeroing a rifle. And then, a recent article from Jerking the Trigger reminded me of that observation… Magic happens when you look through lenses.

If your primary optic on your AR-15/ M-4 goes down, most of us have BUIS (Back Up Iron Sights) of some sort. Easy day, pop those up and press on. What I noticed though, a couple of years ago when reconfirming my iron sights after removing a 1x optic, was that my zero changed. My whole group shifted. The reason for this is science! Looking through lenses changes how we view objects, to include our BUIS, which in turn can shift our zero.

Does this matter? Depends on your intended use of the rifle. At that time I was going hunting, and looking for meat not a trophy, so I was going to put a deer down with a head shot. At which point a zero shift of a inch or two, took an ethical shot to a maiming shot or wholesale miss. If you are Mil or LE, probably want to put a little thought into this…