Regardless of the source of the impulse, the trigger is pulled by a finger for each (difficult to aim) shot.
I dislike the idea of bump stocks, drift cars, street racers, or anything else that reduces the safety of others purely to provide a thrill for the user.
Nonetheless, any ban on these devices will lead to undesirable and unanticipated consequences.
I agree but the BATF has long used the one pull of the trigger, one shot as the legal std. for semi-auto. The Bumpfire or the other trick trigger gadgets make that complicated to rule out semi-autos but ban devices that circumvent the intent of the machine gun language in the NFA. There was something similar in that the ATF ruled in 1982 that even if you make an open bolt design firearm that is semi-automatic--it is too easy to convert to a machine gun. Thus, it is illegal to do so but by the grace of the ATF, they did not make the ban retroactive.
Here is the proposed rationale for the ATF's rule "
In this proposed rule, the Department accordingly interprets the definition of “machinegun” to clarify that all bump-stock-type devices are “machineguns” under the GCA and NFA because they convert a semiautomatic firearm into a firearm that shoots automatically more than one shot, without manual reloading, by a single function of the trigger.
The ATF cites
Akins v.
United States, 312 F. App'x 197, 200 (11th Cir. 2009) (per curiam) as justification to change its interpretation of what constitutes a machine gun. To that end, the proposed rule includes a new qualification that argues even if there is one single trigger pull, a bump stock starts a process that results in firing more than one shot with a single pull of the trigger citing
United States v.
Olofson, 563 F.3d 652, 658 (7th Cir. 2009) as legal support for that conclusion. Realistically, this means a legal challenge to the new rule will probably go nowhere unless the U.S. Supreme Court extends the protections of Heller considerably via requiring strict scrutiny on 2A cases.
Olofson is the case where a guy had a malfunctioning AR15 rifle that discharged more than one shot per trigger pull at a range. It fired bursts and then jammed several times. Evidence in the appellate record is mixed whether or not Olofson installed M16 fire control parts or modified a disconnector purposefully. The appeal centered solely on the jury instructions as to what constitutes an automatic weapon (aka machine gun) under the NFA.
The money quote from Olofson is " As used here, the terms “automatic” and “fully automatic” refer to a weapon that fires repeatedly with a single pull of the trigger. That is, once its trigger is depressed, the weapon will automatically continue to fire until its trigger is released or the ammunition is exhausted. Such weapons are “machineguns” within the meaning of the Act. (NFA)"
Thus, "Specifically, ATF has determined that these devices initiate an “automatic[]” firing cycle sequence “by a single function of the trigger” because the device is the primary impetus for a firing sequence that fires more than one shot with a single pull of the trigger.
26 U.S.C. 5845(b)."
From the data in the federal register, it appears that there are several hundred thousand (up to potentially nearly 500,000) of these stocks that will have to be recalled and destroyed. I do not believe that the ATF has the statutory authority to make this rule apply only in the future (prospective rule). If the device mounted to a rifle makes it a machine gun under the NFA, then it must be registered as such or held by someone who has a registered machine gun, but due to the Hughes Amendment, it cannot be as the registry is frozen. Thus, bumpfire stocks must be recalled and destroyed and upon the final publication of the rule sale or possession of these appears to become illegal under the NFA with all due penalties (at the minimum of thirty days after) and pending legal challenges to the rule. Haven't reviewed the legal authority for the ATF to extend beyond that limit.
Here is the location of the proposed rule
https://www.federalregister.gov/documents/2018/03/29/2018-06292/bump-stock-type-devices
Given the massive number of these, it might make sense to push Congress (if Republicans retain it) to use this as a wedge to reopen the registry for an amnesty period at least. That would let the folks retain their stocks who already have them and bring forth an other illegal ones out of the shadows and have these registered. The justification can be government revenue which bypasses the Senate's filibuster if done under deficit reduction rules in the Senate.