Lands And Grooves Ballistics

M16 Barrel Rifling Pictures

And those portions of the bore which are situated between the grooves are known as lands. Gauge or Calibre- Both types of firearms are classified by the Gauge, or Calibre, of their bores that is by the internal dimension of the barrel A different system of measuring, however, exists for large smooth-bores and rifled arms. Large smooth-bores are measured by the number of Pig. x. Cross-section of a rifled barrel showing the grooves and lands. Pig. x. Cross-section of a rifled barrel showing the...

Extraction And Ejection

After a cartridge has been fired the empty case must obviously be removed from the chamber before the weapon can be reloaded with another round. In the majority of modern firearms the mere fact of opening the breech after firing automatically ejects the fired case but in others the fired case is only partially unseated from its position in the chamber, and has to be removed by hand. This is the difference between ejection and extraction. And since the effects of both extraction and ejection on...