Dan Forrester
I would be worried that vacuum sealing ammo would pull the projectiles from the casings. As you pull a vacume there will positive pressure inside the cartridges. The could espicially be a problem with sealed waterproofed ammo
Bullets are much harder to pull than that, which you will realize if you ever use a bullet puller, either inertial or a collet type. When the gas pressure rises, the bullet is not only being pushed on the base by the pressure,
but the neck of the case expands to release the bullet.
Judging from the graph on page 322 of "Hatcher's Notebook,"
for the old .30-06 Service Cartridge, the pressure when the bullet starts to move is around 400 to 600 PSI as close as I can estimate. (There are some confounding factors there, but that should give you some idea of how tightly the bullet is held and the range of pressures involved to get it moving.)
Let's face it, with a cartridge loaded at a sea-level factory, the absolute air pressure in the case would be 14.7 pounds per square inch, the sea level air pressure.
If you were to suddenly drop the external air pressure on the cartridge to zero PSI, the maximum force from the inside pressure (sea level) on, say, a .308 diameter bullet, would only be 1.1 pounds if my arithmetic is correct.
After all, the area on the base of a .308 bullet is only 0.075 square inches, so multiplying that by 14.7 pounds per square inch gives you that 1.1 pounds of force on the base of the bullet.
I doubt you could pull any bullet out of its case using only 1.1 pound of pulling force... or pushing force from the air pressure inside of the cartridge case.
Incidentally, lacquer or other sealed bullets are much harder to pull "on the reloading bench," as opposed to when they are released from the neck expansion on firing.
Hatcher notes a case where a special lot of tin-plated match bullets designed by Townsend Whelen (yes, him) for the National Matches were very accurate, but could not be pulled out of the case by the usual collet or inertial bullet-pullers. Hatcher inquired of Whelen as to why this was so.
It turned out that the tin plating on the bullet tended to "solder" the bullets in the cases, preventing them from being released by bullet pullers. Still, this ammunition was very accurate because the neck expansion on firing released this "stickiness" and "many fine records" were posted at the range shack with that ammunition.
THE PROBLEM WAS, at that time, in order to minimize bore fouling (which was a biiiig problem with the service rifle and ammo at the time), many shooters greased their bullets anyhow,
despite the fact that the instructions forbade the use of grease on that ammunition.
THE PROBLEM WITH THAT was that the inevitable thin film of grease on the necks of the cartridges prevented the normal and proper release of these "soldered-in" bullets by the neck expansion.
THE PROBLEM WITH THAT, IN TURN, was that some rifles were wrecked from the excessively high pressure developed with the cartridge all corked up real tight at a critical time in the internal ballistics.
That lot was withdrawn and the National Matches continued with ammunition drawn from previous stores.
Terry, 230RN
REFs:
"Hatcher's Notebook," op. cit. and pp 335-340