Hello, Allan;
First of all, you don't register a flinter in Canada. The government has deemed them a 'non gun'. If you want a small caliber, they are sometimes hard to resell. So don't buy an 'offshore' piece! C.V.A., Traditions, to name a few, are very hard to find parts for. It will end up a 'wall hanger', or you could sell it off for parts.
700 f.p.s.? Might as well throw the ball down field!, (or get a pellet gun). I personally, prefer a .50 cal. for all my hunting. Rabbits........you don't eat the head. Squirrels........wouldn't eat a rodent, but you don't actually shoot the squirrel. You 'bark' them. Meaning, you shoot the branch that they are sitting on. The 'shock value', is what kills them. (no matter what the caliber).
Not so much the bore size, but the guy on the end of the gun.
We can talk more, if you like.
Regards
Mark