First: Great looking rifle from the stock pictures over at Savage.
Now this may be dumb, but are you sure the bases are Weaver/Picatinny. I know Savage has been providing them but after all this is a rimfire and traditionally rimfire bases (groves) were much smaller. Can you compare the bases on this gun with a known base. Do the rings work on another base?
But let's assume they are "suppose" to be Weaver/Picatinny. Are you sure this model wasn't made for another market (Europe), but somehow ended up stateside. Possibly the bases are not what we consider "standard".