Listening again to the audio to grab the parts I missed and reading the transcript.
Petitioner (state) is inconsistent in his argument - review the transcripts page 4 lines 23-25
Fletcher argues that a bump stock fires more than one shot...through a self regulating mechanism.
Thomas catches this and gives him plenty of rope to hang his position on this error.
Thomas' killing blow to this is found in page 8 lines 2-7: Fletcher admits that bump firing doesn't require a mechanical aid.
Taking this to the next logical step then if we accept the state's argument that bump firing is automatic firing then ALL semiautomatic rifles and automatic pistols are machine guns since they can readily be modified to automatically fire by simply manipulating holding method and pressure.
On page 8 lines 1-2, Fletcher brings back the self regulating mechanism being the reason a bump stock is a machine gun whereas "manual" bump firing is not. He is in error as the regulating mechanism is the shooter's ability to hold a steady, even pressure while still allowing the forestock to reciprocate (axial movement) AND control point of aim (radial movement).
This is anything but a self regulating mechanism.
A bumpstock does allow the shooter to more easily maintain aim (reduce radial movement) but does not change the need for the shooter to actually regulate the pressure required to maintain reciprocation creating the bump firing.
Barrett then pulls the string on exactly what devices would qualify to create a machinegun mentioning a band or loop to which Fletcher responds that those devices would not be self regulating.
However the ATF has already made self regulating bumpfire devices machineguns when they determined the spring in the Atkins accelerator acted as a regulating mechanism whereby the shooter needed no further input to fire automatically. Removal of the regulating mechanism (springs) in bumpstocks is what put them outside of the NFA.
Barrett then makes the issue clear in page 13 lines 4-8: a bumpstock allows one to bumpfire in a better, more stable way but doesn't change the mode of operation from Fletcher's "manual" bump fire definition.
She then goes on to let him know that she wants to side with him - this is where I see an extremely narrow decision where we win this case but with the caveat that congress can simply rewrite the NFA to ban anything that allows more than an arbitrary firing rate.
Jackson then blathers on about non-textual interpretation of statutes for a while trying to show that if we just change the meaning of words then we can get the outcome we want.
Gorsuch is up next, opening with an open statement that he feels bumpstocks should be banned.
He then goes on to admonish the state for the method they used to ban which didn't include public comment and that by doing so stopped congress from updating the NFA to ban them.
This is where I think we ultimately lose
Gorsuch, Sotomayor, Kagan and Brown will band together to push the opinion that all devices allowing increased rates of fire are outside the 2nd and can be banned but the ban must be handled legislatively. And Roberts will take any opportunity to split the baby and get SCOTUS out of a controversial area and go with the left.
Within 2 weeks of the opinion congress will write a very open definition of firing rate accelerator and Mr dementia will scribble on it as soon as it hits his desk.
And while they are messing with the NFA, they will scale the tax amount and link it to inflation in order to make all NFA devices prohibitively expensive.