<prompt> Calibre is defined as:Distance between two diametrically opposite landsDistance between two diametrically opposite groovesDistance between opposite land and grooveRatio of the length and width of the barrel  <response>: Ans. a. Distance between two diametrically opposite lands Ref: Parikhs 6e p4.26; Reddy 33e p210Calibre 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 2008309Some 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 