Some air rifles punch hard enough to kill deer and fire semi auto.

I have a table for this.

9mm goes for 50 cents per round, .223 and .308 goes for 80 cents per round. Even if you’re buying bulk. In Canada.

22 goes for 20-50 cpr, depending on match grade or not. 17 hmr goes for 50-60 cpr, and IMO, has the best performance for your money.

Ammo availability is one thing, but ballistic performance is another. You can’t take out small game with 223 or 308. 9mm is not a very accurate round either.