Actualy there is a basis to this now intentional misinformation.
There was a system called the Brocock Air Cartridge. It was essentialy compressed air combined with a pellet into what looks a lot like a firearm cartridge.
A truly ingenious design.
You used a pump to pressurize a few cartridges ahead of time, combined a pellet, and essentialy had an airgun cartridge that looked very much like firearm ammunition.
When you fired the gun it just released the energy stored in the cartridge rather than from an air reservoir like most airguns.
So they actualy struck a valve on the back of the compressed air cartridge with a firing pin releasing the air, and then ejected the spent air cartridge much like a firearm does.
So it was basicly a firearm that operated like many real handguns, but used ammunition cartridges that were filled with compressed air instead of gunpowder. There was a little more to the design, but the result is actual firearms and these airguns operated almost the same. They chambered a round and struck the back of them.
Unfortunately because it was introduced in a nation that banned handguns (England) some criminals were willing to go through the effort to convert such firearms to fire puny actual firearm calibers. The airguns were not designed for the high pressures of most firearm cartridges, but they could effectively fire some minor calibers in converted airguns.
This resulted in the clever design being banned in England, the nation the company was based in.
Here is a picture of such an airgun:
Since then antis in such nations have made the case that all bb guns are readily converted, which is far from the truth. They know many people will recall that really being done, and be misinformed to believe it is the case once again. Smoke and mirrors to achieve a desired result.
It is of course possible to use the barrel to essentialy make a zip gun from any bb gun that fires once if a way to ignite the round is setup. Of course a person could just as easily use any other metal cylinder or pipe to accomplish the same thing.
