I'm 99% sure Boyds doesn't offer anything for the older side-button drop mags. I think Hogue or Bell & Carlson did at one time, but whether they're still available or not I have no clue and both would be synthetic. The verbage you need to look for would read something like "Savage 110 flat-top staggered-feed detachable magazine with side button release."

The other option would be to convert the drop magazine gun to a blind magazine which would greatly increase your stock options.