bullet signs

[bob q]

The neck does not "open up " to release a bullet and that is easily proven in many ways . The powder does not start making it's pressure until the bullet hits the lands and forms a plug to seal . My tight neck bench rest rifles have NO neck clearance at all yet release the bullet every time . The cases reload with no sizing . You can pull a bullet out of a case neck with pliers with no expanding of the case neck . How would the gas act upon the inside of the case neck with the bullet in the case neck block the gas from the brass ? The bullet must be pushed out of the way for the gas to reach the case neck . It takes much more pressure to expand a case neck that it does to move a bullet . A primer alone will push a bullet out of a case neck , without expanding the neck at all . That is why you can get a powder " melt down " were the primer pushed the bullet into the bore but the powder does not ignite , it just melts . With a rifle with a large chamber , long throat , undersized bullet , and a powder that does not light easily , the bore will not seal as the bullet has cleared the case without hitting and sealing the bore . That was the problem with Hornady's 7.7mm Jap ammo . The case neck will expand after the seal is made to what ever size the chamber neck is [ minus brass spring back ] as the case make the rear seal .

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