N/A Question about Break-Barrel Power Loss at High Altitude

[MJS]

Hi Gang,

Does anyone have any data (empirical is OK) that shows the velocity of a piston airgun at different altitudes?

I'm considering buying a break barrel rifle that shoots 14.3 gr at 750 fps at 500' altitude. I live at 6500'. Velocity wise, I'd like to know what to expect with the same pellet.

I ask this question because last year I bought a new (.22) HW30 that shot 425 fps in AZ, but 350 fps at 6500' with the same pellet.

Is it simply a linear relationship? Based on the gas laws, probably not. But I don't know.

Thanks!

(ADDENDUM: This is not about PCP's. I know PCPs are more consistent at altitude. I'm asking about break barrels.)

 

[EMrider]

I live at about 4000', and often travel to another location very close to sea level. I have chrony tested my R7, hw50s and hw97k (all in .177) and found that the 4k altitude change reduces my power by 8%-10% depending on the gun. The R7 is closer to 10% and the hw97k is about 8%. Not sure if the curve is linear or log, but those results have been consistent over quite a few years.
R

 

[MJS]

Thanks! That's very helpful info. The more info the better. I can plot points and attempt to formulate this relationship.
I think this is an important topic.

 

[Mycapt65]

Get a PCP they're nearly unaffected by altitude

 

[MJS]

Get a PCP they're nearly unaffected by altitude

^ I understand that completely. I was just asking about break barrels. Thanks.

 

[Mycapt65]

^ I understand that completely. I was just asking about break barrels. Thanks.

Ok, some people aren't aware of that and I was trying to be helpful

 

[Mycapt65]

There's a formula for altitude power loss on the Vortek website

 

[MJS]

There's a formula for altitude power loss on the Vortek website

Great! Thanks I'll check it out.

 

[MJS]

Found some good data here:

Yellow Airgun Forum Archive-Finally, Springer altitude testing completed with pics and decent data volume

Introduction Thank you First, I'd just like to thank my handful of awesome customers; especially the guys who helped make this project possible. Too m

www.tapatalk.com

 

[Paddywonka]

Never knew altitude effected air gun performance.