Calibre is defined as:

Ans. a. Distance between two diametrically opposite lands (Ref: Parikh's 6/e p4.26; Reddy 33/e p210)Calibre is defined as distance between two diametrically opposite lands.'The calibre of a rifled firearm is measured between a pair of diametrically opposite 'lands' across the bore. Textbook Of Forensic Medicine And Toxicology: Principles And Practice By Vij (2008)/309Some Important Terms Related to FirearmsCalibreDistance between two diametrically opposite /andsQActionAction means the assembly of the firing mechanism of the gunQ.BallisticsScience of the motion of a projectile