Calibre is defined as -
The synopsis of forensic medicine & toxicology ; Dr k.s narayan reddy ; 28th edition ; Pg.no. 122 It is also called gauge . Also refer fig 8-16 (cross section of a rifled barrel)
Distance between two diametrically opposite grooves
Distance between two diametrically opposite lands
Distance between two diametrically opposite lands and grooves
Ratio of the length and width of the barrel
Mechanical injuries