I had always thought that the suppressors were tuned for bore size and the volume and velocity of expended gas during the firing impulse for the chambered cartridge. I'm not sure how it could be flexible enough to be efficient with a 5.56 and an opening of 7.62 or be able to efficiently delay enough gas for a 7.62x59 while working well with a 5.56x45.

...but I am definitely no expert on suppressors.
[popcorn]