Truthfully, in my experience running a lvl 7 over a 10 is always a bad idea. Just the weight difference alone is enough to have a drastic difference in kick, and multiply that by a higher rate of fire and it only gets worst. Plus, even to this day, a lvl10 is STILL one of the best bolt systems to use on fragile paint.
If anyone would want to run eyes, I would recommend a lvl 10 with the stock lvl7 spring for the best of both worlds.