I've been reading the debates here about energy levels in airguns. Which to me is a little strange because, after all, these are airguns. At least in velocity airgun pellets equal match grade rimfire ammunition. Even some lower grain standard bullets. But for the energy transfer it would make more sense to just shoot low velocity rimfire ammo because of the weights of the projectiles alone. A 700fps forty grain bullet is delivering astronomical fpe at impact compared to an airgun pellet. The wind bucking ability of forty grains cutting the air ought to by itself be enough reason to choose low velocity rimfire ammo. On top of that, a rimfire rifle spitting low velocity bullets is nearly silent. To earn that kind of terminal fpe in an airgun you need lots of power which means the airgun actually becomes the louder of the two rifles.
Then you have the issue of accuracy. Which is infinitely more important than power. I can pin down wasps and Asian beetles with rifles shooting between five hundred and seven hundred fps. I have pistols that, were I to actually practice enough, I'm sure would do the same. But the rifles are sa-weet to shoot and that's the other point. No firearm is like an airgun. Vice versa, the line's already been blurred. Half the point being made here involves the economy of power. Discovering just how little energy is required if perfect accuracy is attained.
There's a subtle elegance in the airgun. You won't discover that elegance by searching for more velocity or energy. Its in the smoothness of the firing cycle of a well maintained airgun regardless of its power. If the gun is rough or harsh it might just be too powerful to be enjoyed in its proper element.