You shouldn't use dangerous weapons while hunting Pokémon in real life, because you're more likely to harm the little critters you're hunting than capture them.
Instead, you should check out this video by Joerg Sprave of The Slingshot Channel to see his Pokéball launching pumpgun in action.
It's the most hardcore way to catch 'em all, and actually makes being a Pokémon hunter look kinda cool...
-Via Laughing Squid