The stock in a firearm located in the rear of the firing mechanism where one's shoulder is held when shooting(noun)
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Use "buttstock" in a sentence
"The recoil pad and buttstock both twist off without tools."
"I don't look at myself when I shoot of course, but when I shoot offhand I try to neither have my elbow out at a 45 angle nor down against my ribs but rather at an angle, sorta southeast with a nice pocket in my shoulder for the buttstock."
"If you want to retain a wood stock with an increased length of pull, you may want to consider Boyd's buttstock for the Lee Enfield and stain it to match the existing forend."