How do pellets fly in subzero temperatures...?

[Flintsack]

Right before dusk it was eight below here in Minnesota. I decided to test the cold air.

I haven’t been able to shoot for a week. My only option is to rest the rifle on the windowsill, otherwise the Maroge is so bad there’s not a chance. I also have a cover on the top of the window that lays over the scope. The scope and my left hand are outside.

I just decided to see what would happen, so I bombed a few at 100 yards into the snowbank. I was pleasantly surprised with the groups. I shot a single shot into the bank first as my aim point, I’m pointing my pen at it. Then I shot five shots. One was about 2 inches, one was well under that.

this started to get fun. So I decided to shoot a couple groups on paper. One was fantastic. The other one was really good with one shot that I pulled to the right. Very easy to do when shooting from a window sill at 100 yards... and your left hand is very cold.

Conclusion from this small sample size. This rifle seems to shoot really well in very cold air. It also shot about an inch and a half low.

I was shooting my red wolf high power 17 at 30 foot pounds with Crosman CP heavies.

Both pictures are sideways.

 

[Guest]

So glad I don't live in Maryland anymore. Too cold. I just need to move to Florida now

 

[18.13]

Cold air is thicker. I have shot at the same target when it was 15* and when it was 109* there was a .4 mil difference just what Chairgun said it would be at 94 yards.

 

[2L8]

Cold air is thicker. I have shot at the same target when it was 15* and when it was 109* there was a .4 mil difference just what Chairgun said it would be at 94 yards.

Excellent info 18.13 

 

[Flintsack]

My test was very analog. It’s nice that the results lineup with the digital answer.

mike

 

[L.Leon]

That is really cold weather shooting, an inch and a half low at 100 yards? I guess that proves cold, really cold air is dense. Good shooting! Only had time to send five shots down range after work today. Too cold and dark too soon, but Spring is coming!

 

[marquette]

Only 13 below here right now. Where are you at in Minnesota? A friend in Ironton posted a picture of her car thermometer and it was -30 this morning on the way to work.

 

[Flintsack]

Luckily, I’m not that far north. Just south west of the twin cities near Carver. 


At least it hasn’t been windy.

mike

 

[Mooner625]

I don't know about the air density but I think that the temperature affects the gun.

Last Sunday it was sunny lite switching wind and 0 degrees out. I took two of my RAW'S out to the 50 yard targets they shot fairly well for the conditions ( wind mirage) except some shots would drop out of the 10/9 ring buy 1/2 inch or so and they would even sound different. I am thinking that the cold was affecting the regulator or the hammer fall. 

In the afternoon at 5 degrees I did the same thing with my Crown and it seemed to do fine with no unexplained shots. 

That was the end of my outside shooting for a while.

 

[Crusher]

Not only is cold air more dense, but you have to consider that your gun is air driven. The cold just lowers all the pressures. I find that to my home range, my guns are shooting about 1/2" low at just 30 yards. But they are also shooting maybe 50 fps slower at the same settings. If I take the gun inside and let it come to temp, then test, the gun returns to the original tune. That is until it gets cold again



Crusher

 

[Flintsack]

The last couple replies were interesting, talking about the cold air also affecting the rifle.


There is no doubt that is the case. I’ve shot field target for many years, obviously in the fall we get cold weather. Everyone adjusts their rifle in the morning. Of course that can cause problems as it warms up. When it’s this cold your scope can definitely see things differently, this is in addition to your rifle changing. 


In this case the rifle was actually warm. The only thing outside was the barrel and the objective of the scope. With a curtain draped down over the rifle.

interesting and good observations, just wanted to give you all the data points specific to this very small sample.

I really wanted to test the change in the air not the rifle. Certainly not a perfect experiment. However I already applied the knowledge gained on the hunting forum this morning.

mike

 

[Airgun-hobbyist]

It was shooting outside in 20° weather yesterday and it did effect how the gun sounded from shot to shot at times, depending on how long I took to shoot or fill. I think has to do with the difference in air temperature in the cylinder as well as the atmospheric conditions frosting internal components at the previous shot. I've had the outside of the barrel and moderator frost up in slightly warmer weather (just below freezing conditions with more humidity in the air) so I said suspect that the inside of the bore and valve ports were freezing frosty vapors as is sat for an extended period of time.