Altitude Effects On 38 Super Rounds

[redwoods]

I live at 8150 feet in Colorado. If I shoot a 38super and it makes power factor up here, will it change if I go to Arizona or Florida?

I know that golf balls go farther out here because of the less dense air. I am guessing that will also be true of my bullets.

Redwoods

[AlamoShooter]

when I went form San Antonio to Colorado I did not get a mesurable change.

[shred]

I live at 8150 feet in Colorado. If I shoot a 38super and it makes power factor up here, will it change if I go to Arizona or Florida?

I know that golf balls go farther out here because of the less dense air. I am guessing that will also be true of my bullets.

Redwoods

PF won't change to any reasonable amount. Long-range ballistics might, but unless you chrono at 100 yards, you'll be fine.

[Bear23]

I lost 20 fps in my open gun going from 3600 feet and low humidity to 800 feet with higher humidity.

[shred]

I lost 20 fps in my open gun going from 3600 feet and low humidity to 800 feet with higher humidity.

Wow, same temperature & chrono? 20 fps is a heck of a lot to lose for bashing through 10 feet of air.

[shane c]

i live in mississipi with hot weather and high humidity. i worked up a load with 7625 at a 171 pf in the colder months. went to arizona to shoot the world shoot qualifier and chronoed a 161. how in the world does my fps drop 70-80fps?? 80 degrees in arizona at the time by the way

[GentlemanJim]

Some powder will have a burn rate change ...up or down per temp.

Test a known load a few rnds from the freezer....and some in the hot sun.

Then you will see the diff.

@ 40 deg my load was 166pf ...@80 deg it was 177pf

Jim

[Jake Di Vita]

7625 has always been ultra reliable temperature wise for me. Are you sure that your powder measure didn't back off accidentally?

[shred]

I find 7625 to go faster when the temperature gets lower, which is 'backwards', but it works, especially as I usually end up chronoing in 95 degrees and 95% humidity..

[dfwmiket]

I find 7625 to go faster when the temperature gets lower, which is 'backwards', but it works, especially as I usually end up chronoing in 95 degrees and 95% humidity..

Hmmm......thinking ahead to Area 4, maybe?

[shane c]

jake the powder measure didnt move. we measured it when i got back home. they were asking for new sun screens for the chrono and i think that might be the reason why.. bad chrono. see the same thing happend to BJ Norris. his pf went from 172 normal down to a 162 out there.

[BritinUSA]

My PF was the same at Rio as it is in Colorado. They only had a single chrono setup. I prefer to see two in sequence , the chances of getting two bad ones is incredibly remote. I heard part of the discussion about the screens so I went through the chrono at the end of the day and was okay.

[Bear23]

I lost 20 fps in my open gun going from 3600 feet and low humidity to 800 feet with higher humidity.

Wow, same temperature & chrono? 20 fps is a heck of a lot to lose for bashing through 10 feet of air.

Well, the second chrono was the match chrono at DTC, not my CED. So who knows.