A bump fire stock that attaches to a semi-automatic rifle to increase the firing rate at Good Guys Gun Shop in Orem, Utah, October 4, 2017. (George Frey/REUTERS)

I’ll stop ranting about this soon — I promise — but with the final rule in hand, I wanted to dot one last i in my year-long crusade against the Trump administration’s attempt to ban bump stocks via regulation rather than by working with Congress to pass actual legislation.

To reiterate the problem once again: The current statute defines a “machinegun” — i.e., a heavily regulated automatic weapon — as a “weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.” This simply does not describe bump stocks, which don’t affect the relationship between the trigger’s functioning and the number of shots fired at all. Every time the trigger functions, one bullet comes out.

Bump stocks work by helping the user pull the trigger incredibly quickly. As the ATF itself once put it, “the shooter must apply constant forward pressure with the non-shooting hand and constant rearward pressure with the shooting hand,” and this pressure, along with the gun’s recoil, is channeled into repeated pulls of the trigger as the weapon bounces back and forth against the user’s trigger finger. This has the effect of making a normal semiautomatic gun fire rapidly like a machine gun. But it’s not a “machinegun” as the law defines it. Even the Obama administration thus had to approve these devices for sale.

How did the ATF get around that? The agency added this to federal regulations:

For purposes of this definition, the term “automatically” as it modifies “shoots, is designed to shoot, or can be readily restored to shoot,” means functioning as the result of a self-acting or self-regulating mechanism that allows the firing of multiple rounds through a single function of the trigger; and “single function of the trigger” means a single pull of the trigger and analogous motions. The term “machinegun” includes a bump-stock-type device, i.e., a device that allows a semiautomatic firearm to shoot more than one shot with a single pull of the trigger by harnessing the recoil energy of the semi-automatic firearm to which it is affixed so that the trigger resets and continues firing without additional physical manipulation of the trigger by the shooter.

Besides giving up the game by admitting that the trigger is still resetting for each shot, this has the effect of scratching out “function” and replacing it with “pull,” even though a trigger can function without being pulled. And since that isn’t enough — it might be said, as I said above, that a bump stock helps the user “pull” the trigger faster, and that the gun still fires once for each of these “pulls” — the rule then just explicitly singles out bump stocks and blithely asserts they allow users to “shoot more than one shot with a single pull of the trigger.”

This is all made worse by the fact that the ruling is retroactive. People who legally purchased these devices now must destroy them or turn them in.

I can never guess what the courts will let a regulatory agency get away with. But the ATF does not deserve to get away with this.