I'm not sure how your rifles shoot, but this is how my AK shoots with Tula steel-cased ammo and stock iron sights...
Good shooting! I wish my eyes were that good. I couldn't do that with my A2 on that target.
Were you using something bigger than the 2.5" square as an aiming reference? At 100 yards I pretty much need a 6" black circle to center over the front sight post. I don't know if I'd even be able to see that square.