altitude effecting pressure

[cal hunter]

Does going from sea level to higher elevation effect the pressure on loads for your rifle . I know temperature will make a difference when the temperature goes into the 100 degree mark but would like to know if it gets worst with altitude

 

[Doom2]

Simple answer is no.

 

[Recon$$]

POI can be affected. Hell even my five iron goes further at elevation.

 

[Petey308]

No, but it will affect external ballistics of the load.

 

[cal hunter]

okay thanks

 

[jshepherd61]

Does going from sea level to higher elevation effect the pressure on loads for your rifle . I know temperature will make a difference when the temperature goes into the 100 degree mark but would like to know if it gets worst with altitude

The correct answer is no and yes! Altitude in itself will not effect the ballistics, now weather which is a derivative of altitude does effect true ballistics. Humidity, temperature and dew point is a major factor on powder burn rates, bullet flight/drag. Being from Colorado and hunting above 10k for elk and having family on the Oregon coast and hunting Rosevelt elf at see level, I see drastic change in poi as much as 7" depending on humidity!

 

[Petey308]

The correct answer is no and yes! Altitude in itself will not effect the ballistics, now weather which is a derivative of altitude does effect true ballistics. Humidity, temperature and dew point is a major factor on powder burn rates, bullet flight/drag. Being from Colorado and hunting above 10k for elk and having family on the Oregon coast and hunting Rosevelt elf at see level, I see drastic change in poi as much as 7" depending on humidity!

Only thing I wanted to clarify here is that while humidity does affect the powder's burn rate, in the form of moisture content in the kernels themselves, it only changes where the powder is stored and while the rounds are being loaded. Once the case is sealed with the primer and bullet, it shouldn't change after that. Then it's just temperature of the powder and changes in drag of the bullet encounter in flight, like you said, from more or less air density and moisture content in the air.

And for what it's worth, I buy Boveda packs and n the 52% variety and store them in my powder containers. It keeps the powder at a consistent humidity.

 

[BrentM]

Internal ballistics, no. External ballistics, yes. So in the case of the case, ha, the answer is no as each have stated. Litz has some very good info on this subject if you care to study it

 

[jshepherd61]

Only thing I wanted to clarify here is that while humidity does affect the powder's burn rate, in the form of moisture content in the kernels themselves, it only changes where the powder is stored and while the rounds are being loaded. Once the case is sealed with the primer and bullet, it shouldn't change after that. Then it's just temperature of the powder and changes in drag of the bullet encounter in flight, like you said, from more or less air density and moisture content in the air.

And for what it's worth, I buy Boveda packs and n the 52% variety and store them in my powder containers. It keeps the powder at a consistent humidity.

Not quite correct, burn rate is not instantaneous powder burns down the length of the barrel, humidity is instantaneous so once powder starts to burn the local humidity takes effect manipulating the burn rate in the barrel! If any of you use QuickLoad you will see this in the calculations. Example: 7mm STW 168gr ABLR loaded with 80.5gr Retumbo in a 29" barrel the complete burn is 27.3" down the barrel. That is 27.3" of burning that is humidity effected

 

[Damage Inc.]

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.

 

[cornshank]

Here is my observation, at higher elevation you are out of breather easier ,so your rifle tends to wobble around ,when shooting offhand, so yes your POI will vary a lot.
Food tastes better to, I don't golf, so no 5 iron info.

So the relation to pressure is the pressure is on to make the shot .
Hey ca hunter , what area of California are you in ?

 

[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.

Funny complete opposite of what world-renowned ballistician Litz, says up at the AFA.

 

[Damage Inc.]

You can shoot a round off under water.

If ambient humidity were a factor in internal ballistic combustion, how would shooting a round off under water be possible?

PS…. Litz is a ballistic consultant. As such, like any good consultant, his numbers will always trend closer to the desires of his employers, than to actual ballistics.

 

[jshepherd61]

You can shoot a round off under water.

If ambient humidity were a factor in internal ballistic combustion, how would shooting a round off under water be possible?

PS…. Litz is a ballistic consultant. As such, like and good consultant, his numbers will always trend closer to the desires of his employers, than to actual ballistics.

you are 100% correct however I and other have discharged under water, try it if you get 68% of the velocity send me the data.