Impact of cold temperature on ballistics

[toupiny]

Hello to all, I went deer hunting with my son at the end of November, since being in Canada, its was darn cold... My son, usually a decent shooter, missed, successively, two bucks at short range with his Brown Bess. Both bucks were standing at the bait at about 15-20 yards...

He believes that both shots went above target. He got disgussed after the second miss and went for the truck to think about his passed sins.

Good thing dad was there with his 1861 Springfield, so at least we collected a doe at the same spot. But my shot was a bit high also, compared to my aiming point...

Can anybody enlight me on what could have happened?

Thanks

 

[Black Hand]

Hello to all, I went deer hunting with my son at the end of November, since being in Canada, its was darn cold... My son, usually a decent shooter, missed, successively, two bucks at short range with his Brown Bess. Both bucks were standing at the bait at about 15-20 yards...

He believes that both shots went above target. He got disgussed after the second miss and went for the truck to think about his passed sins.

Good thing dad was there with his 1861 Springfield, so at least we collected a doe at the same spot. But my shot was a bit high also, compared to my aiming point...

Can anybody enlight me on what could have happened?

Thanks

Cold air is more dense than warmer air...which could affect POI.
http://longrangeshooter.com/2009/02/temperature-effects-on-zero/
https://gundigest.com/more/how-to/training/ballistics-air-temperature-bullet-flight
http://noblecotactical.com/blog/external-ballistic-factors-that-affect-bullet-trajectory

 

[Caterpillar Hunter]

I'd have a hard time believing a total miss at 20 yards was due to colder air. Maybe a bumped sight? I assume thorough searches for wounded deer were done.

 

[Black Hand]

If it was me, I'd suspect "buck-fever" or an error in estimating distance. Having had the same thing happen, I had aimed at the whole deer rather than picking my spot...

 

[jmdavis]

I have found major velocity differences based on temperature. The rule of thumb from the US Army Marksmanship unit is 1 moa per 20 degrees Fahrenheit. The rounds impact lower.

 

[Juice Jaws]

If it was me, I'd suspect "buck-fever" or an error in estimating distance. Having had the same thing happen, I had aimed at the whole deer rather than picking my spot...

Black Hand I think you are dead on. I was going to say the same thing but you got there first. Buck fever does funny things, even if you have kill many before. I have miss things that was impossible to miss, but I did. Aim small miss small.

 

[RHensley]

For some reason I shoot a little high off hand and on off the bench.

 

[tenngun]

I hat been out all day about two miles from my home in Arkansas. It was about four in the afternoon that I started to walk home. About a mile from home a deer jumps out in front of me not fifteen yards and ten feet higher in elevation as it was a little uphill ( in the Ozarks you can only go uphill, I don’t know the physics involved) he stopped in my path an stares at me. I moved slowly to shoulder-my gun and shot. Smoke, blind and hearing the sound of deer running through the woods. I waited for a bit and and reloaded. Then went out to track him. Feet dig deep leaving good track I walked.... and walked... and walked, no blood, no stagger,picking clear path as he ran. After a mile or so he stoped running, he hadwent in half circle. And back to a walk.
I missed him at a range I had split balls on-an axe, or popped candle lights... how that happen?
The next day I test fired to make sure my sights were not moved... they weren’t. Just bad luck... buck fever... Grandfathers little joke? No! German Angles with weak bladders...that’s what did it.

 

[George]

Colder air is more dense. More dense air creates more drag for the ball. More drag slows the ball. Slower balls fall further in any given distance, so they will hit lower.

That said, at 15-20 yards the effect would be so small you couldn't measure it.

Check the shooter, may be a problem there.

Spence

 

[Carbon 6]

Temperature can effect anything. It can slow balls, shrink steel, warp wood, stiffen grease, affect chemical reactions, change point of impact etc. However the biggest affect is usually on the shooter. for example, cold fingers can make Jerky trigger pulls and a heavy coat can change the length of pull and sighting, moving the shooters point of impact.

 

[Artificer]

Also when it is cold enough, it might be shooting during a major shiver that throws the aim off.

I have never hunted in weather quite as cold as it gets in Canada, but one time we hunted when it was -28 F due to the wind chill factor. My trigger finger just didn't work as smoothly as it did at higher temperatures and that introduced a bit of a jerk to the trigger pull, which also affects the impact of the bullet or shot to go higher than intended.

Gus

 

[BrownBear]

I'd have a hard time believing a total miss at 20 yards was due to colder air.

I have to go along with that or some explanation other than ballistic changes.

I do a whooooole bunch of small game shooting in cold weather, most of it within about 30 yards using calibers from my 30 cal (.290 balls) to my Bess. If there's a change in POI from summer sight-ins, it must be measured in fractions of an inch at 20 yards. I've never noted change in POI when aiming at bunny eyeballs and still hitting the head.

 

[azmntman]

Buck fever gets my vote. And/or extremely poor catastrophic follow thru.

I missed a sure shot once at a water hole. 50 yd shot everything calm and clear, no wind. Bang, deer busted into the water and I prayed NOOO dont die in the water...he busted thru, circled off so slowly to about 20 yds from me and then the powder smell caused him to vacate the area mach 2. After thoroughly checking for signs of any hit (which at 20 yds were not visible on his body) I returned to camp and centered a chew can at 80 yds like a drill press. I now (5-6 years later) believe I shot and jerked up at last mili second to see the hit. Catastrophic follow thru.

2 years ago I had a monster white tail (cous) deer come in at 35 yds and for the 1st time in 45 yrs of hunting I got buck fever so bad I couldnt keep the sites on him. He watered and went away happily never knowing there was a guy in a blind 35 yds away with 250 hearts beats a min trying to ruin his day. I was NOT expecting to see a cous, let alone what I still feel was a record book buck. I was after a spike or forked horn mulie. Embarrassing buck fever. Least yer son got off a shot

 

[TerryK]

If the deer hears the rifle, they crouch down a bit to leap. So it is a good idea to aim low.
I personally think the lock time is longer when it is near 0.

 

[Loyalist Dave]

Did You Sight In at the range wearing the same clothes that you had on in the cold weather?

Especially if you don't have some sort of rear sight on that bess..., a thick, winter coat is going to change the cheek-weld and the spot where that happens, AND going to give the shooter a different feel to the butt placement on the shoulder too. Add a hat that comes down over the ear, or a full head cover of knitted material like a mask with only eye holes....very different when you shoulder that gun......Classic smoothbore mistake...., same for modern shotguns too.....

See I've done it too. That's why I think I know what happened

The goose gun shoots great at the skeet range with no rear sight and only a vented rib and a bead, but put on the winter clothes and get into a goose blind, and even when they are close, you THINK you're looking down the barrel in a proper manner, but...., head's a bit high, you shoot over TOP of the birds every time. So IF your son thinks he's shooting high..., he probably was, but not from the denser air in cold climate. Denser air would slow the ball down faster, so the ball would drop more going to the target...colder air lowers point of impact a tiny bit.

LD

 

[BrownBear]

That's a valuable insight Dave. I bet you're closer to the truth than this speculator.

 

[Dean2]

I am a Canadian too. I have shot Flintlocks in -40 weather. At 100 yards there is not discernible difference in POI from where it is at +25C. If your son is shooting over it isn't the temperature effect on POI. There are lots of good suggestions above, anyone of which could be a contributing cause. Shooting at live game is not the same as punching paper.

 

[Wisconsin Relic]

I vote for buck/doe fever. As mentioned, it does cause us to do strange things. In some hunters, a close deer ramps up the problem. A deer at 100 yards may not get us revved up much, but one at hand shaking distance can send us over the edge-as far as doing unexplainable things. I personally think excitement and adrenaline brought on by a very close big game animal are much more likely factors to cause a miss than is cold air.

 

[Palatine]

toupiny: When you say bait I envision an elevated stand; was your son shooting DOWN at the bucks? If so it should have been necessary to hold somewhat low. He may be correct in thinking that the bullets went right over their backs. Still, 15-20 yards is so close that little correction was necessary.

 

[SDSmlf]

Grew up near Canadian border in western New York. Think Buffalo. Have lived in North Carolina for over 25 years. Still hunt every year in WNY. Have sighted in numerous traditional and non traditional firearms in NC and found no change in point of impact at hunting distances when hunting in the cold weather of WNY. Likely buck fever or possibly heaver clothes changing point of impact.