This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
Not a part of a firearm - 
Select and explain. 
A. Bolt, B. Piston, C. Extractor, D. Muzzle
B: Piston
Answer: B: Piston 
Explanation: Parts of firearm weapon are:-


Barrel: Which has two ends: breech end and muzzle (breech end may have a chamber and an extractor).
Action: Consists of

(a) breechblock (bolt),
(b) firing pin or striker pin or hammer,
(c) trigger.

Grip (buttstock and magazine.