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
Rifling is ? 
Select and explain. 
A. Shoening of barrel, B. Narrowing of barrel at nozzle end, C. Spiral groove inside nozzle, D. All
C: Spiral groove inside nozzle
Answer: C: Spiral groove inside nozzle 
Explanation: Ans. is 'c' i.e., Spiral groove inside nozzle Rifled arms The bore of the rifled weapon is scored internally with a number of shallow spiral grooves varying from 2 to more than 20, the most common being 6. These grooves run parallel to each other but are twisted spirally from the breech to muzzle. These grooves are called rifling and the projecting ridges between these grooves are called lands. Examples of rifled firearms are Pistals, rifles and revolvers.