The entire sequence of events, as mentioned above, is ordinarily referred to as the barrel time, although the true barrel time is more correcdy that between the instant at which fire is produced in the primer and the bullet has left the muzzle of the gun. The time between the releasing of the sear and the production of fire in the primer is the lock time and has nothing to do with our handloading
Firing pin has just struck primer, driving cartridge case forward and seating the rim of cartridge against back of barreL Note clearance between cartridge and chamber, (exaggerated for purpose of Illustrating: what happens,) also headsp&ce between head of cartridge and face oi bolt.
Primer explodes, igniting the powder. Extremely violent action of the primer compound drives the primer partly out of case and back against breech block, also drives powder grains forward against base of bullet.
Powder burns almost instantaneomlv, developing pressure ol from 30,000 to 50.000 pounds per square inch.. This pressure expands the thin forward part of cartridge case against the walls of chamber, but cannot expand the thick part near cartzidgc head. Hence front part of cartridge grips walls of chamber tightly, while extreme rear part does not. Neck of cartridge caso expands and gas escapes around bullet before It starts to move.
Bullet moves forward, sealing the bore as it does so. Back end of cartridge moves to the rear until it comes against breech block, while front part of cartridge remains locked in place by pressure or gas holding it against chamber walls. Cartridge stretches at S and may rupture If headspace Is excessive.
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