Although I've read about it here, I was amazed at the effect of paralax when trying out my new ACOG with BAC.  At shorter distances, the reticle shows one point of aim with both eyes open, then jumps several inches when I close my weak eye.

Is that typical, and how do you deal with it?  I don't have that experience with my eotech or aimpoint.  Thanks.

This is called phoria and I believe it is discussed in the large "Best General Purpose Optic" thread tacked above. It will also be covered towards the end of your ACOG mannual. Phoria is worse for some people than others and it discusses why very briefly in the owners mannual. Several inches is much much more than I have noticed? How far away is the target you are looking at when you do this test?

BAC is only for close quarters shooting. The advanage of BAC is that you have the ability to use a magnified optic like a dot site when you are cruising around in fluid movement type fast paced shooting environments. The only time you would really be utilizing BAC is at fairly close ranges.

Therefore, when you check to see how much of a difference phoria makes for you, test it on targets, I dont know... say about 10 yards away or so? See what the differences are at ranges like that. For me is is only a matter of a couple inches at most. A couple inches usually doesnt amount to a whole lot of anything in fast paced shooting like CQB.

If things are so tight that an inch or two is going to be crucial, dont use BAC is possible. Just take whatever time may be available and make the well aimed, precise shot using the magnified image. It shouldnt take you longer to do that than it should to get a clear sight picture/sight allignments with irons.

Yes, what you are describing is just a natural side effect of binocular vision. The amount the dot will shift with the ACOGs will depend on several factors (even with zero phoria, you will still see dot shift and a majority of the population has at least some phoria - check your manual out as it discusses this also).

For me, the dot shift at indoor ranges happens to be just enough that if I place the unmagnified dot on the leading edge of a silhouette target, I'll hit dead center mass. If it's a shot that needs precision though, I'll generally slow it down a fraction of a second and used the zoomed view though.