@old grump - my answer was vague,however, the notion of a perfect rifle for everything from squirrels to deer is pretty wide open. if you do a lot of walking in the woods, squirrel season is a lot longer than deer season and provides way more opportunity for shooting. Not that a .357 won't put down a squirrel (sarcasm), but will waste most of the useful hide/meat. To each his own
To the OP, My answer would still be a shotgun. When hunting squirrels, stoke it with pellets. If it were deer season I would keep it filled with slugs. If I came across a squirrel while hunting deer, I would simply, swap out for for a different load ... If I didn't care about the deer.
If I were to to lean a different direction from my first, reply (based off your request) it would be that savage 24 that petahw posted. It's great to dream on the Internet and living a place where we have so much choice.