Impact of cold temperature on ballistics

[toupiny]

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

Thanks Black Hand, it must have been a sum of factors, we always grease our guns with Wonder Lube 1000 + and this type of product tends to thinken a lot under cold temperature. Since we use tight match of bullet and patch in the Bess, it could have had an influence together with a small variance caused by density of the air...

The following week we went to the firing range with the Springfield and my son's Enfield: using minie balls at 50 yards, from the bench, we were both erratic to say the least, not even touching the target in some instences. In warmer weather we group within a few inches. In the case of a minie could the lead become hard to the point of not decently expend in the barel?

 

[Black Hand]

Thanks Black Hand, it must have been a sum of factors, we always grease our guns with Wonder Lube 1000 + and this type of product tends to thinken a lot under cold temperature. Since we use tight match of bullet and patch in the Bess, it could have had an influence together with a small variance caused by density of the air...

The following week we went to the firing range with the Springfield and my son's Enfield: using minie balls at 50 yards, from the bench, we were both erratic to say the least, not even touching the target in some instences. In warmer weather we group within a few inches. In the case of a minie could the lead become hard to the point of not decently expend in the barel?

Any ideas I might give you apply only to roundballs, as I've never shot anything else. My suggestion, for what it's worth, is switch to another less waxy lube - An oil (vegetable/olive/peanut), lard, Mink grease, Bear grease (the lube I use). While I very much doubt the lube remains frozen upon firing between friction and ignition heat, it might help. Develop a roundball/patch/lube/powder combination that works for your gun in cold conditions.

 

[toupiny]

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.

John, for the first buck we searched for a while following the tracks in the snow, but we did not find a single drop of blood nor fur either where the aninal was standing or afterward... The second one was even more obvious: after hearing the shot it rose its head, did not notice my son's blind and continued eating as if nothing had happenned. Hearing the shot I left my spot to go lend a hand to the shooter and I am the one that scared the deer away.

I guess you will wonder why my son did not reload while the deer was eating... Well, he did not bring an extra charge! I guess a case of a young man self assurance... After his sulking in the truck, I believe experience will prevail from now on...

 

[toupiny]

Any ideas I might give you apply only to roundballs, as I've never shot anything else. My suggestion, for what it's worth, is switch to another less waxy lube - An oil (vegetable/olive/peanut), lard, Mink grease, Bear grease (the lube I use). While I very much doubt the lube remains frozen upon firing between friction and ignition heat, it might help. Develop a roundball/patch/lube/powder combination that works for your gun in cold conditions.

Thanks Black Hand, we will try to develop a better cold weather charge and lube.

 

[toupiny]

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.

Thanks JMDavis

 

[toupiny]

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.

Carbon 6, I believe you are right if we amalgamate your proposal with JMDavis' it must have been the issue. We guess he shot high because of the result of our bench shooting with Minie ball the following week: but, since the miss occured with a patch and ball, it could as well been under the deer, hard to say...

 

[toupiny]

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

Gus, it occured an hour maximum after getting on the hunting spot, it could have happenned but it sounds like a short time in his case to get stiff fingers. Thanks

 

[toupiny]

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.

BrownBear, I would certainly not like to be wearing bunny ears in front of you! LOL!

 

[toupiny]

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

azmntman, I totally agree with you: he got to see some fur and got two chances of putting meat in the freezer. In one way, it's luckier than freezing his buts waiting without seeing anything, as it happens often to the best of us! Thanks for sharing your hunting stories.

 

[toupiny]

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

Loyalist Dave, he was in deed wearing a tuque and thick clothing: we will have to try to reproduce at the bench what type of influence clothing might have had: we will see...

 

[Loyalist Dave]

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

Thanks... drove me nucking futs for a full season until an older guy told me I needed to get my head down when shooting (we were in the same blind) He explained to me what I mentioned in my reply above. Eventually I had to get a clip-on rear sight for the vented rib as by then I'd developed a bad habit. Once I forced my head down with the rear sight..., geese in the bag!

So...for a Bess or a trade gun....Some guys like to put a couple of washers under the tang screw to lift it a tiny bit.... then they index the groove in the top of the tang screw to the barrel's length...so they get a notch to look through at the front sight. Others get a 3/4" brass angle piece from the local hardware store and put it under the tang screw and then modify the upper part to be a rear sight. works good for goose shooting too....

LD

 

[toupiny]

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.

Thanks Dean2, for couriousity's sake: where are you located? Personnaly I am in Quebec

 

[toupiny]

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.

The blind is set on a small mound, maybe five feet higher than the bait: not much of an elevation... Lets say that you need to keep quiet and hold still!

 

[FishDFly]

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.

I might believe that with bow hunting, I cannot believe that if a deer hears a rifle shot, he has time to crouch down to leap.

How is the lock time longer?

So, if a deer is further off, the lock time is faster?