It seems to me that it is a hard way to get 1200 ft lb of energy from a gun. Just pick up a box of 12 gauge shotgun slugs for your shotgun and you have 2500 ft lb, or pull out a 300 Winchester Magnum and have 4000 ft lb. Why try harder to "get 'er done" ?
Lewis and Clark used big bore semi auto loading air rifles on their adventure . They could drop a deer at 75 yards , amaze the Indians and float down river and no gun power barrels to tote or get wet when they capsized. I think they had around 16-20 shots before repumping the guns. Since it wasn’t a war, it was a great idea ! it’s all very interesting story , of how the guns were stolen and smuggled out of Russia for their trip.
Air guns is far better to kill many types of game, it’s fun and sporting …to different things entirely. Many people use big bore modern air rifles to hunt wild hogs and much more . Even big bore air pistols will kill wild pigs . There is little to zero recoil from these types of air guns making them extremely quite and recoil less in the field . I don’t need shotgun to kill small game , 1953 Sheridan Super grade is very deadly accurate, cheap to use and ammo never goes bad .
Air guns definitely have their place for small game.
Most are much more reasonable priced and ammo doesn't have to come from a single source.
(Does anybody produce those "slugs" beside Zeus?)
I have a Gamo Hunter .177 which I'm sure could drop a deer with a close-range, well-placed shot.
Single stroke, break barrel single shot.