I recently fired an Arsenal SAM-7, and a Hungarian SA85M, both of which had a MoJo rear sight installed.  From a bench, at a 50 yeard target, with both PMC and American Eagle ammo, the best I could do was 3 inch groups.

The good thing though, was that at least the groups were tight. . . .   The standard front sight on both of these rifles is still in place.  I did some adjustment with both the MoJo and the front sight.

Any thoughts, comments, or suggestions for improvement?

From my experience, the selling point of the MoJo, is the quick target acquisition--a vast improvement over standard sights.  

Not saying that the rifle might not be alittle more accurate... But you are talking about 7.62x39 AK's. If you got 3" out of them be happy .  Thats good groups with these type of rifles. Seriously..... WarDawg

Quoted: But you are talking about 7.62x39 AK's. If you got 3" out of them be happy .

Yes, the 7.62 x 39 variety.

My shooting skills are above average, and learned in the Army.

You should be getting better. Best I've personally experienced w/7.62x39 AKs is honest 2" groups at 100yds using Wolf ammo & a scope on my SLR-95.
Tomac

Is the PMC and Federal stuff .308 in diameter? Would you do better with the standard AK loads of .311 bullets?

Quoted: Is the PMC and Federal stuff .308 in diameter? Would you do better with the standard AK loads of .311 bullets?

Bingo!

This is the main problem with the majority of U.S. manufactured 7.62x39 ammo.