I've only trapped for one year, and used a .22 on raccoons and some possums, but most of the grinners that I catch I use my digging trowel (OK it's not really a trowel it's more of a 1" thick piece of steel rod with angle iron digging face.) I have never had an animal "come to" or even twitch after hitting with the handle end of this tool. The weight of the steel makes it almost elementary to dispatch the animal, gravity does much of the work and the only muscle involved is in lifting and aiming. One of my buddies caught a very angry yote and didn't want to take the .22 pistol near it so I used my trowel and it didn't make so much as a yelp or take another breath.
Althought I in my neck of the woods a 12 year-old can carry a gun (not pistol though), I have no issue with them using an apropriate bludgeon to take care of their catch. As long as the tool is based more on weight than speed, then the animal will not come to, and will not suffer.
Many times with a gun, especially pistol, the shot is not perfect and can make far more effort neccesary than would a club of some sort. In the example of that yote, a pistol in the hands of a poor shot would be far less effective than my 3 foot shovel handle. On smaller, safer, and all together more docile animals such as coon, the gun is an almost 100% weapon, but on large, unruly animals, a close shot is not always possible and adrenaline can cause a bad case of inaccuracy. A rifle is the answer to the accuracy problem, but is not always practical on longer lines, or in heavy cover where the added bulk slows the trapper down.
So what all my pussy-footing around has gotten to is that a firearm is great, a club in the hands of an able bodied trapper is good, and anything used that takes more than one attempt to subdue an animal is probably not the best choice. To each his own, but I feel that as long as the animal doesn't endure prolonged suffering in it's death, then the method of dispatch is effective and humane.