Climatic impact on ball drop

[moleeyes36]

Several months ago a friend of mine moved to Wyoming, about 3 hours drive north of Rock Springs.  He can't find anyone in the area that shoots black powder but he recently got his rifle out and went to a local range.  He found that his ball was striking "significantly higher" (that's all he said) with the same charge, patch, and lube he used back here in Florida.  He said he's sure his sights hadn't been moved during the trip out west.

There is certainly a very big difference in climate between where he was in Florida (10 feet above sea level and 80 to 90 percent humidity) versus the high and dry climate of where he is in Wyoming.  Could this change actually cause a "significantly higher" round ball strike at 100 yards?

Mole Eyes

[JPK]

I would believe that going from sea level to over 6000' would have more effect then climate.

[Daryl]

Quite possibly correct - higher elevation = thinner dryer air.
We always had hunters check their rifle zeros at base camp (about 3,000ft. ASL) when I guided.  If from some areas close to the ocean, there was usually re-sighting necessary, with their rifles or bows with sights, however, some lads from Texas who were "instinctive" shooting archers didn't notice any difference. Guys from Eastern Washington, Idaho or Montana saw no difference, usually, unless "the sights had been bumped or damaged by baggage handlers, of course.

[Candle Snuffer]

When I moved from Ohio (850 ft above sea level and plenty of humidity) twenty five plus years ago to NW Nebraska (3700 ft above sea level and a dryer lower humidity climate area) my muzzle loading rifles shot 4 inches higher. Had to re'sight them all. I firmly believe elevation and weather conditions makes a difference.

[Molly]

A close family member was a 13E20.  Best he recalls when calculating fire direction info a good many variables were part of the picture.  Temp, humidity, wind speed, direction etc etc etc etc and more etc.  But "altitude" as characterized here was not a part of the calculation so he says. (If his mind is clear tonight.)  The elevation of a target vs the elevation of the artillery piece was a factor but when firing from an elevation of XXX to a target at elevation XXX altitude was not factored in.

So his conclusion is it don't matter diddly!  But maybe firing a round ball differs for an 8 incher or a 175.

[Don Steele]

Thinner air at higher altitude would be my answer to why his P.O.I. changed.  I have some past experience "setting" ATA   ( Amateur Trapshooting Assoc.) Trap targets.
To be a "legal" target, the trap has to be set for the target to achieve a minimum flight distance of 49-51 yds. in still air. Think of that as p.o.i. in this discussion. At sea level, you have to put more speed on the target to make the distance. In higher elevations, Colorado for instance is a place I have experienced this, you can set the targets to fly slower, and they still make the distance. Folks who have shot a lot of the faster targets at lower elevations always comment on how Colorado targets seem to "hang in the air" longer...they're just flying slower to essentially impact at the same place on the field. If you use the same speed in the mountains that is used down here in Florida...the target flies farther ( i.e.: higher p.o.i.).

[Standing Bear]

3 hrs N of Rock Springs and can't find a ML shooter?  He ain't trying. My first trip to Wyoming in 37 years. Shot in 2 Rendevouz and missed 2 due to conflicts. Encampment and Ten Sleep, Wyo. Gunnison CO.  Pinedale had one.   West Yellowstone.  Seems there's one or more every week.
TC

[Dan]

Air density is greatly influenced by pressure altitude and temperature, not so much by humidity.  Point of fact, humid air is less dense than dry air.  One half of our atmosphere is found below 18,000' ASL.