Cold Air

Break out that twany springer and shoot indoors

Hi John, you will not have much luck shooting from inside to outside when the temp differences are great. Mirage alone will wreak havoc. If you just went out into the cold and shot you would likely do much better. Your scope is not really pointing where you think it is with super heavy mirage like you will encounter when doing what you are doing.

Mike 

John

I can’t shoot at all right now unless I put the rifle on the windowsill with the objective well outside the window. 


Probably worse for me because I’m using higher magnification, which usually increases the mirage substantially. I’m assuming you’re shooting at 16 X.

mike

I use to shoot out the window, but hated letting old man winter in. A hot water bottle under your vest or coat is good for at least 4 consecutive 5 shot groups. Go outside and shoot, unless it's raining, then I pop up the deck umbrella. 

It’s been below zero all week. They’re just simply is no shooting outside, at least not air guns, The pellets are too small to load with gloves on.

When I was a younger man we would head up to the range in just about any temperature, as long as it was above zero. And we had a clubhouse and a fire. Below zero, forget it. No fun

mike

@flintsack, below zero is definitely too cold for fun shooting.

shooting inside to out is a recipe for great frustration! 

As Mike stated the marriage can be unbelievable, you don't really know where to Aim? and you really can't wait for the boil to snap (it doesn't) even if there is wind and you have flags.

I did it just today for some trigger time no expectations, 13deg. outside, no fun out there today!

Here in Montana, with the great temperature shifts we have from winter to summer, I have to adjust my elevation on my scopes by as much as 8 clicks to get back on target at say, 200 yards, when shooting firearms. Diffraction of light, sometimes called "heat mirage" is the main issue. If using powder that is temperature sensitive, that is an issue as well. For air rifles and the shorter distances they are shot at, it is not as much of an issue.

For the powder issue, using Hodgdon Extreme powders, or Ramshot TAC, gets rid of most of the velocity shifts, which again is not much of a airgun issue. Changes in air density does have some effect at longer ranges.

Light diffraction causes an exponential shift at long ranges and is most noticeable when shooting firearms due to the longer ranges that shooting occurs. The shift is not a fixed angle, but a continuous curve. When corrected at 200 yards, the correction will not be right at 400 yards if you see a lot of heat distortion in your scope. More correction will have to be dialed in. Since I live in Montana, long range shooting is the norm for me.

For rimfires and airguns, if I set my scope just after sunrise on a summer day, at a prairie dog in the early afternoon, I will be shooting over the PD heads if I don't click down at least 4 clicks on a hot sunny day with lots of heat distortion visible in my scope.

For my 7x57mm Mauser CZ 550 hunting rifle, I set my hunting zero at the 300 yard tic mark since I sight in at 300 yards, which is a typical mule deer shot around here. I do this at a similar temp that I expect to be hunting at. The other tic marks will be reasonably accurate from 100 to 500 yards, as the 300 yard tic mark is in the middle. Do NOT zero your rifle at 100 yards and expect the 500 yard tic mark to be accurate in hot weather, because in hot weather it WILL NOT be accurate, though it might work in cold weather or at dawn when heat distortion does not exist.

You will just have to do LOTS of practice to learn how to handle heat distortion at various distances under field conditions.

In a military sniper manual, you will see that military snipers have to adjust for every 1000 feet of elevation change and every 20 degrees variation in temperature. Having shot quite a bit in Montana where we have wide elevation and temperature shifts and long range shooting, I can affirm that the military sniper advice is quite correct.

Phil

My barrel impact changes in the cold. My air pressures also wreak havoc on my precision. Winter SUCKS!