altitude effecting pressure

[jshepherd61]

The only humidity that effects burn rate, is the humidity inside the case. There's no ambient air added into the combustion process (maybe not no air, but very minimal air). The bullet seals the air on one end, and the case expands to seal the air on the other end.

Once the bullet leaves the muzzle, then humidity comes into play, due to its effect on air density.

Actually there is unless you pull a perfect .30 vacuumed and seal your barrel before pulling the trigger! Otherwise you would have no ignition or burn! Your barrel is full of the air and environmentals you are discharging in!

 

[Doom2]

Actually there is unless you pull a perfect .30 vacuumed and seal your barrel before pulling the trigger! Otherwise you would have no ignition or burn! Your barrel is full of the air and environmentals you are discharging in!

Sorry but your logic is incorrect.

Their is a very small amount of air in the chamber but it is insignificant and does not contribute materially to the combustion of the powder. the air forward of the grooves is sealedl away from the powder once the bullet engages the lands and is pushed out with the bullet.

As mentioned earlier, a cartridge will fire in water or in a perfect vacuum. The oxygen required for combustion is available in the nitrocellulose and/or nitroglycerin. C18H21N11O38