Even some of the lightest factory loads of smokeless powder develop higher peak pressures. We are talking 10,000 PSI out of the plinking loads for a firearm VS 3000 PSI for a full power charge out an air rifle on the first shot. Hunting rifles are often designed to push 30,000 to 50,000 PSI or even higher in some magnum cartridges on a regular basis.
I don't foresee air rifles ever being a tool employed for self defense.
To crank the external tubes up to higher pressures the engineers will have to add cumbersome material, or start exploring more expensive materials. It's either that, or you need a larger caliber to get more power. The larger the surface area of the projectile, the more force that can be applied with the same amount of pressure, but in making that decision the engineers have to compromise on the number of consistent shots before the pressure is significantly depleted. Even with the added barrel length, air rifles will always be comparable in power only to handguns, not large game hunting rifles.
So, there you go. There's little to support that air rifles are pertinent to any regulatory schemes of small arms. You'll just have to wait for the blasters to come out, and by then the resistance will have light sabers.
