Could anyone offer some advice on the best set-up for a 14.5" barrel A2?  I can only get about a 4-6" 100yd grouping with the iron sights.  I think the shorty sight picture might be messing me up.  I am not new to shooting, I always qualify "expert" w/ the M16.  

I'm considering getting either an Aimpoint like the Army uses or a reflex II. Any thoughts?  Also, should this rifle be shooting more accurate w/ iron sights?  Or is that about right? Thanks

check your sights, ft and rear. make sure they are not damaged.
mine shoots much better than that, right outa the box
good luck

It's the short sight picture, I can barely do 6" with mine, but with a 4X scope, I grouped a 3/4" 3 shot with handloaded Win 64 Power Points.

My shorty AK shoots great,...but then again, I've never fired a 20" barrel, so maybe Im just used to the shorter one....You might try ordering the front and rear night sights from Bushmaster, they have dots at 3 o'clock, and 9 o'clock on the rear aperature, and a dot on the front post.  Having reference points might help you compensate for the shorter sight radius than you are used to.  I thought about getting a set of them for mine, think they run around $85.00
At any rate,...yes, your rifle should be able to shoot more accurately than 4" at 100 yrds. I can get 2" without any problem, better than that if I feel like taking my time, and being more disciplined.(but that's not as fun)[:D]

How did you zero your rifle? I have a 16" carbine M15A2 from Armalite that I have zeroed in at 25meters. I shoot at 100 yards , but I don't get the greatest groups  because of the zero. Shooting at 100yard I'm always around 2-3inchs high. So I have to aim little lower to hit small targets at 100yards. I also use the standard front sight that covers up a lot of paper at 100yards.I usually get 3-6inch groups. That's okay with me because it is a battle rifle and that's how I have it zeroed. I think I will put a match sight on the front though to help a little. I'm more worried about left and right off than I'm at up and down the way it is set up. When I was in the Army also and you remember how big those pop up silhouettes are.If you got a good zero and a decent shot just aim at top of chest and down they went. I'm sure if you have a battle zero on it, it shoots high at point of aim at 100yards. I would not sweat it too much. I have been thinking of getting a Reflex II with the triangle and see what kind of groups you will get. Although I have never looked at one on a range so I don't know what range is most practical to zero it at.

No Slack!