But a rifle in responsible hands is not dangerous, however once you get drunk the most responsible person you know could kill a whole family before they get home from the pub. Again you have to look stats, what kills more people, alcohol or guns? Alcohol.
Lets look that the practicality of both Items.
Gun:Sick or injured animals can be put down humanely. Pests, that cause farmers and native animals alike can be 'dealt' with. (whether you agree with killing pests or not, you can't deny that they aren't pests)
Alcohol: I really can't see this being needed at all.
You sir, are wrong. I CAN deny that they aren't pests, and I WILL *emotes with top-hat. monocle, and waxed mustache, nose turned upwards*
Calling something a pest is highly subjective and seeks to de-legitimise whatever worth it has. Feral cats could be called 'pests' to native birds, but to both feral cats and native birds humans are a pest. Hell, people on this forum might consider you a pest for even posting here

Following that thinking they may not show you respect or offer insults and the like...
No, not pests. I'd like to think of it as... a challenge
And I agree, I don't know how alcohol is going to help a sick or maimed animal that is beyond recovery, other than give it one helluva drunken last hurrah...
Yes, there are people who own rifles that are responsible, just as there are responsible drinkers. I think it's too simplistic to separate fatalities into neat and orderly categories, let alone try to rank them without considering the complexities of their nature and the relationship they share with one another. Who knows, you could have a drunken idiot driving a car swerving across the road on the wrong lane at high speeds firing his gun at oncoming traffic in a game of chicken ;D