I am considering the Burris 332 which is a 3X magnification or one of these two, Primary Arms 4X or the Primary Arms 2.5X magnification. My question is if shooting less then 100 yards will scopes that are magnified (or any scope for that matter) shoot high if you have them zeroed in at 100 yards. Maybe I am not understanding .223 trajectory correct.

No, if you're zeroed at 100y, your groups will be below your reticle from 0y (2.6" low) to 50y (~1.3 low), 75y (0.6" low) etc....  Basically the bullet makes a straight line from 2 something inches below your reticle where it leaves the bore to your zero distance.  Make sense?

With a 100y zero that's about the top of the 223 trajectory, it's generally under that coming up before and under that going down after.

Yes. Thanks.

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I own the Burris 332. It is a good scope but having said that it has to be picked for the right purpose. I hit what I aim at with it and like others have said, it depends on the distance ones zero is at for where point of aim point of impact is. During 7 yard tactical drills, my aim point is about an inch from the top of the bull to hit center of the bull.

Now for things that could be issues depending on how one is using it:

Eye relief is short meaning that your AR better be an ORC Flat top. The 332 has to be the very first thing mounted at T1. My nose touches my Wilson Combat extended charging handle release when I have a full sight picture. This is fine because it gives quickly repeatable cheek placement and the AR15 doesn't really kick. Down side is I can't wear my Impact Muffs when firing this rifle (collapsible stock so cheek is on tube) if I want proper eye relief (I use plugs). So this also means that any BUIS rear sight must go in front of the 332. Upside is even if the battery is dead the 332 still has a black reticle so to need the BUIS, the 332 has to be smashed or completely broken at which point I'm taking it off anyway.

Next its a permanent 3X so this means shooting with one eye open through the sight, other eye closed or you will get a headache and probably miss more then hit. Since the 332 is a 3X, one also can not CO-LO iron sights either for the above reason so they must be flipups.

If ones eyesight is getting bad and one HAS to have magnification, the 332 works wonders. Same if one is shooting 200 yards or more most of the time having one eye closed anyway. But if one is looking for a true tactical sight for both eyes open shooting at under 25 yards, the 332 is not your sight. One is better off with an Aim Point or no magnification higher end sight. Does the 332 work for close contact tactical drills, it does with one eye closed and the targets are not firing back, moving, or more coming at you out of the 32 foot field of view (remember that is at 100 yards, we are talking under 10 foot FOV at 15 yards).

If you have any specific questions or concerns, I would be happy to share what I have learned or found out while using the 332.

Thanks for the info