Irons in the Fire is calling BS on the ATF.
From what the ATF says, this isn't about something being "easily convertible". This is because the Airsofts are too good a replica of the real thing. Executed in plastic and low-quality metal, but gee, they look like e-e-e-e-vil black rifles.
Anyone stupid enough to try to shoot anything out of them is in more danger than the target, me thinks.