Changes in case pressure with elevation

[SethWiley86]

Hey fellas I'm curious to know what happens as far as case pressure when developing a load at 256' above sea level then trying to shoot it at say 6k above sea leave,. Everyone knows air density is thinner bullets fly with better trajectories yada yada yada but does your pressure decrease or increase inside your case. In my personal opinion thinner air density less humidity basically means less resistance therefore less overall pressure so if you could tell me your opinions or facts it would greatly be appreciated thanks

 

[Fuzzball]

Re: Changes in case pressure with elevation

Well, the tiny weight of the air to be expelled from a bore is meaningless.

The cartridge is a closed chamber so the inside pressure will be unchanged even if it's fired in space.

The atmospheric pressure is near 15 psi at sea level so the difference in gaged chamber pressure in space would be effectively greater by that 15 psi but, as a percentage of some 55,000 psi, that means nothing. Meaning we won't see any meaningful difference in gaged chamber pressure at any altitude.

 

[SethWiley86]

Re: Changes in case pressure with elevation

Ok great. Thanks for the info. It's been an ongoing discussion between a friend and I and I've always thought but never been able to test that when you create a load at 256' sea level it will still be a safe load way above see level. His opinion differs which is normal and I respect that but his opinion is that when you create a load at lower sea levels significantly higher ones you would need a lower charge to prevent a load having added pressure.