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Page Number: 16

12 

GARLAND v. CARGILL 

Opinion of the Court 

by engaging the trigger a second time and thereby initiating 
a new firing cycle.  For each shot, the shooter must engage 
the trigger and then release the trigger to allow it to reset.  
Any additional shot fired after one cycle is the result of a 
separate and distinct “function of the trigger.” 
  Nothing changes when a semiautomatic rifle is equipped 
with a bump stock.  The firing cycle remains the same.  Be-
tween  every shot, the  shooter  must  release pressure  from 
the trigger and allow it to reset before reengaging the trig-
ger  for  another  shot.    A  bump  stock  merely  reduces  the 
amount of time that elapses between separate “functions” 
of  the  trigger.    The  bump  stock  makes  it  easier  for  the 
shooter to move the firearm back toward his shoulder and 
thereby release pressure from the trigger and reset it.  And, 
it helps the shooter press the trigger against his finger very 
quickly thereafter.  A bump stock does not convert a semi-
automatic rifle into a machinegun any more than a shooter 
with a lightning-fast trigger finger does.  Even with a bump 
stock, a semiautomatic rifle will fire only one shot for every 
“function of the trigger.”  So, a bump stock cannot qualify 
as a machinegun under §5845(b)’s definition. 
  Although ATF agrees on a semiautomatic rifle’s mechan-
ics, it nevertheless insists that a bump stock allows a sem-
iautomatic rifle to fire multiple shots “by a single function 
of the trigger.”  ATF starts by interpreting the phrase “sin-
gle function of the trigger” to mean “a single pull of the trig-
ger and analogous motions.”  83 Fed. Reg. 66553.  A shooter 
using  a bump stock,  it asserts, must  pull  the  trigger  only 
one  time  to  initiate  a  bump-firing  sequence  of  multiple 
shots.  Id., at 66554.  This initial trigger pull sets off a se-
quence—fire, recoil, bump, fire—that allows the weapon to 
continue firing  “without  additional  physical  manipulation 
of the trigger by the shooter.”  Ibid.  According to ATF, all 
the shooter must do is keep his trigger finger stationary on 
the bump stock’s ledge and maintain constant forward pres-
sure on the front grip to continue firing.  The dissent offers