Just to nitpick a little here: Though it may effect your personal results, the sight you're using does not determine the inherent accuracy of the rifle.
Iron sights are a bit more difficult to use than an optic. Focus on the front sight, so the target and rear sight are a bit blurry. That's where you get your best results.
Passing inspection with a 4 MOA group is one thing, but many of those rifles will do much better. It would seem hard to believe for some today, but a rack-grade M-14 was required to put five rounds into just over 6" at 100. I have a few acquaintances who swear they’re getting MOA accuracy from an AK. My best so far with an AK is a Russian Vepr .223 caliber AK: two consecutive, three-shot group of under 1.5" at 100 yards with Wolf 62 gr ball. That was with standard iron sights.
I have other AKs that are pie-plate accurate at best.
If you have broadband, you might like this video I did last summer. That's a cheap Romanian AK (SAR-1) with an AImpoint sight on it:
http://www.ultimak.com/AKClays.htm
The camera was on a stand, so we didn't know until afterwards that a lot of the good action was out-of-frame to the right. That gravel pit is now closed to shooting. I also didn't know that the only reason you can see these hits was because the cliff in the background was in shadow and the targets were in sunlight (good contrast). We did the same thing with an M1A, but the targets are all invisible, the cliff being in sunlight.
