>>888226>1.77 caliberthat's, like, 3x .50 BMG with some leftovers. Sure you don't mean .177? :)
Seriously though - it's physics.
.177 pellets are usually around 8 grains in weight, though there is some variation and they can go as low as ~7 grains (still talking about lead, not alloy ones), and as high as 11+ grains (even more with something like piledrivers, but those require FAC rated PCPs to be at all effective).
A typical .22 pellet, on the other hand, is around 15 grains.
Now, since Ek=1/2mv^2, velocity is a big factor for muzzle energy, but that also means losing velocity is a big factor as well.
.22 pellets are more effective for hunting only partially because the greater area means better energy transfer (case in point - pic related have excellent energy transfer in .177 even in 16J rifles), but primarily because higher mass means more inertia - ergo the .22 pellet is going to resist velocity change better than .177, and after travelling, say, 30-40 yards it will retain more of it's initial velocity, and therefore - energy.
the lower velocity (around 180 m/s versus ~250 m/s for .22 and .177 respectively - shot with aa tx200hc) means more drop for .22 pellets.
tl:dr - longer pellet flight time means gravity has more time to act upon the pellet before impact.
