I've been looking too and came across the PCP air guns.
Take a look at the FX Revolution on YouTube it is a semi-auto 12 shot.
Check out some of the YouTube EdgunUSA videos.
Also check out the Benjamin Rogue 357 cal. some videos with it taking down deer and pigs.
Evanix Conquest semi/full auto air gun with 20 round mag
Just some I have looked at so far.