should warne fixed/permanent rings work on a egw picatinny base?

this is for my savage 220 slug gun.

the warne rings appear to have a narrower slot than the base of the egw base and when tightened up the can slide forward and back quite easily. I can't believe this is how they're suppose to be...?

it's as if the base has a 1/4" slot and the base on the rings use a 1/8" slot.

thanks.