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Page Number: 18

14 

GARLAND v. CARGILL 

Opinion of the Court 

of  its  reasoning,  insisting  that  the  bumping  motion  is  a 
“function of the trigger” only when it initiates, but not when 
it continues, a firing sequence.  But, Congress did not write 
a statutory definition of “machinegun” keyed to when a fir-
ing  sequence  begins  and  ends.    Section  5845(b)  asks  only 
whether  a  weapon  fires  more  than  one  shot  “by  a  single 
function of the trigger.”  
  Finally, the position that ATF and the dissent endorse is 
logically  inconsistent.    They  reason  that  a  semiautomatic 
rifle equipped with a bump stock fires more than one shot 
by a single function of the trigger because a shooter “need 
only pull the trigger and maintain forward pressure” to “ac-
tivate continuous fire.”  Post, at 10; see also Brief for Peti-
tioners 23.  If that is correct, however, then the same should 
be true for a semiautomatic rifle without a bump stock.  Af-
ter all, as the dissent and ATF themselves acknowledge, a 
shooter  manually  bump  firing  a  semiautomatic  rifle  can 
achieve continuous fire by holding his trigger finger station-
ary and maintaining forward pressure with his nontrigger 
hand.  See post, at 5; 83 Fed. Reg. 66533.  Yet, they agree 
that a semiautomatic rifle without a bump stock “fires only 
one shot each time the shooter pulls the trigger.”  Post, at 
4; see also 83 Fed. Reg. 66534.  Their argument is thus at 
odds with itself. 
  We  conclude  that  semiautomatic  rifle  equipped  with  a 
bump stock is not a “machinegun” because it does not fire 
more than one shot “by a single function of the trigger.” 

B 
  A bump stock is not a “machinegun” for another reason: 
Even if a semiautomatic rifle with a bump stock could fire 
more than one shot “by a single function of the trigger,” it 
would  not  do  so  “automatically.”    Section  5845(b)  asks 
whether a weapon “shoots . . . automatically more than one 
shot  . . .  by  a  single  function  of  the  trigger.”    The  statute 
thus specifies the precise action that must “automatically”