So is the suggestion here that an "accurate" gun should exhibit zero difference between that first cold bore shot and the rest? As a hunter I have definitely experienced a lower POI when the gun and ammo are 28 degrees vs 78. Maybe an inch over 100 yards. Much more so with a stone cold suppressor (which also contributes barrel droop). Now, if we're talking left/right (windage), I agree-- and my guns don't shift POI like that. But surely there is some physical difference in the speed of chemical reaction, friction coefficients, bore constriction (no matter how minute), etc.
Or we talking about a completely different phenomenon? I am talking about centerfire rifles, is this just about 22LR?
-Stooxie
You are describing dense air becoming a factor in this. While it's true that density does factor into POI, it has 0 to do with the cold bore flier problem.
Point number 2 as we discuss this: I will lead you to things that are rarely thought of in the science of inherent accuracy.
I tried to tell them over on Rimfire Feminist Central........but they condemned......you know, because they know it all.
If you prove one of their leaders wrong, all hell breaks loose because they can never be incorrect about anything and if someone points out misleading information.,,,,,look out. Very few, if any of those people have studied this the way I have.
Maybe I'll have better luck here. So here we go.
When you reference inherent accuracy levels while shooting in 28 degree weather, you should be aware that the composition of your entire gun changes. I'd bet you didn't know this. Or maybe you do, considering I went back and red your post again where you reference " constriction."
Every metal component in that gun changes. It's not the same gun as it were in 78 degree weather.
This of course will indeed effect accuracy.
All metal components will contract. This includes the barrels bore. And its chamber.
There are instances with 2 -8 ounce triggers which function fine at 78 degrees. Bring the temperature down to 28 degrees, the gun will either slam fire due to partial engagement, or not engage at all, as the bolt just cams down with 0 engagement. This is caused by metal contracting. ( shrinking) Whatever youd like to call it.
Many years ago , Anschutz had an article about this concerning their Biathlon rifles. Anschutz would increase the bore dimension slightly in those guns for shooting in the extreme conditions you are discussing, in attempt to accurize the gun for extreme cold.
I wish I could find that again, but im afraid its long gone as this has been many years ago.
Other thoughts have risen with the claims that once a shot is fired that it heats the barrel enough to bring it back to normal.
This is NOT the case. It's not even close. Here is why.
Once your barrel reaches 28 degrees, it becomes a heat sink. Fire a shot, and before you can blink your eyes twice that barrel and bore has cooled back down likity split. Just as if a shot was never fired.
With 22's anyway. Centerfire may take slightly longer but the same applies to it.
T.S.