This is one of my pet peeves about frozen. I often buy the Petco brand Gourmet Rodent in packs of three. They almost always come in 3 sizes, small, med, large hopper e.g. There can be as much as 7 or 8 grams variance between large and small.
I have 2 snakes I feed these to, exact same weight. So one is always getting cheated a little out of his meal. The largest one I tend to toss to my 200g python cause it looks a little large for the corns. (unless a 20g hopper is okay for a 110g corn snake).