There had been several legal battles over forced-reset triggers, which replace the typical trigger on an AR-15-style rifle. The government for years had argued they are essentially illegal machine gun conversion devices because constant finger pressure on the triggers will keep a rifle firing essentially like an automatic.
It's basically a spring that forcibly resets the trigger even if your pulling it.
So if you keep squeezing, it's going to keep shooting.
So they say "essentially" a full auto, but they really could have dropped the "essentially", that shits full auto: