
Why?
After a year or two in airgunning, I chose .22 caliber.

(1) Different calibers have different uses, and buying "just the right tool for the job" is great. I probably would if I could!
But getting a bunch of specialist guns is financially not feasible at this point.
So, instead of getting many specialist guns, one for each shooting scenario, I try to get a few generalist guns.
➔ So, the caliber has to be suitable for many shooting scenarios (even if it is not "ideal").
(2) Only one caliber means: I only need to buy only one caliber for my projectile/barrel testing.
It keeps my bank account happy (and my wife, too, as I avoid filling yet another drawer with lead toys).

(3) Only one caliber means I only need to research one set of projectiles: •the selection of pellets and slugs, •their ballistic coefficients, •the terminal performance of hollow points at different velocities.
All that is plenty of tedious work, and certainly not all of it really fun.

(1) .22cal offers me a significantly higher ballistic coefficient (BC) over .177cal — and .25cal doesn't have a hugely improved BC over .22. The BC is of course for better wind drift resistance (as I'm still terrible at reading the wind, it's just so finnicky!).
(2) For urban hunting my guns need to be quiet, so PCP it is. And I fill them with a $-friendly hand pump: A larger caliber isn't great for quietness nor for handpumps.
(3) For hunting I want a fairly flat trajectory so that my point blank range (PBR) is fairly long.
Sure, the .177 would offer me an even flatter trajectory than the .22 — but even my low powered gun (15FPE) gives me a PBR of 11-33y and that's good enough for many of my shots.
Quarry at longer ranges usually gives me time to laze and dial, they are helpful in that way.
(4) .22cal makes larger holes in my quarry than .177. This I find good (and my quarry not so much, I suppose).

(5) The larger the caliber the less attractive the pricing, variety, and availability of projectiles — so again .22cal is a good middle.
(6) .22cal is just easier to handle for loading the breech/the magazine, the .177 are pretty tiny....


Yes, your mileage may vary!

So, what is your opinion?
And why?
Matthias