I recommend against trying either, but I think your analogy might fail because of the broad spectrum of responses possible in both cases.
In both cases a surprise (punch or shot) that fails to reduce function of an attacker or victim might go unnoticed (in terms of function) in the heat of the moment (until the longer term damage - swelling, blood loss, etc... - kicks in), but both also have a variety of potential responses ranging from immediate incapacitation to little effect at all based on the damage done by the impact.
A punch is perfectly capable of being lethal if well placed and hard enough. A bullet is perfectly capable of passing through the body with little to no immediately recognized effect.
So, what exactly are you assuming would be the same different between a sucker punch and a "boxing style" hit to a ready target?
Please keep these punches limited to .22 caliber