I've owned about 15 of the small frame Martinis in various calibers, including a .357 (which couldn't hold a candle to yours, by the way) and I've yet to own one that wouldn't shoot well. If the .357 cartridge shoots well and the range at which you're looking to be able to take a deer is within the .357's capacity, I'd leave it alone, shoot it a bunch to get comfortable with it and go hunting with it in the fall.
