the holes on the spider are not completely symmetrical.
↑This. I just moved the same (Stronglight CH3) chainring from some cheap square taper cranks to some Shimano 5700s, and my previously wobbly drive train is now nicely uniform around the crank rotation.
I have the same problem on my Primato cranks. Apparently the holes on the spider are not completely symmetrical.
It´s a nightmare to tighten the chain.