Shooting rimfire in the cold

At minus 20 I find that CCI Standard Velocity drops about 2 inches more at 100 yards than in warmer weather. I don't know if it's the powder being cold, or the cold air being denser than the warm air.
Denis
 
There's a simple reason why any .22LR ammo "drops" more when it's cooler. MVs decrease as temps fall and increase as temps warm.

Why? The "explosion" that propels the bullet toward target is the result of a chemical reaction. The rate of chemical reactions is temperature dependent, more energetic when it's warmer than when it's cooler.
 
Maybe 'single-load' with extras in your shirt pocket . . . and after a few rounds to 'warm up the barrel' ? I did 'OK' last week with mags kept there @ -10C but only at 25y and 50y - and not particularly accurate rifles anyway. A Sav-64 w-red-dot and Stevens 66 with irons. And both are awkward to 'single-load' with cold fingers.
 
I have no real experience, only what I've seen shooting a couple of matches. The carbon barrels tend to hold velocity better, as well as accuracy, when it's cold. Maybe it has to do with the cold contracting the barrels making the bore tighter?
Anyone have any other, and better experience with this?
 
Thinking more about this, the barrel bore shouldn't shrink on contraction with the cold, I'd will grow, od will shrink. Not matter how miniscule, dealing with 0.001" tolerances that jam up up, it will most definitely be a factor as well. How much of one, I'm not sure.
 
Well, I was going to shoot an ORPS and NRL22 match today. I can report my experience of attempting to shoot in -30C, I withdrew after 2 rounds. Everything seemed fine at sight in, MV just 20fps slower than in normal temperature. I hit nothing in round 1, went back to the sighter board and had no idea what was going on... up for round 2, again a big fat 0. Back to the sighter board at 50 yards, I finally see two hits land, a full 2 Mil vertical between them, that's 3.6 inches. It was like my rifle became a smooth bore between sight in and round 1. Along with Fail-To-Fire malfunctions, next round slowly feeding up from the magazine, foggy glasses and freezing my gonads off, having zero accuracy sealed the deal, I was outta there.

Deductive reasoning suggests the interplay of extreme cold with the ammo lube and/or moisture in the bore from firing to be the cause of accuracy loss. I was shooting RWS Special Match. While petroleum based bullet lube may be usable in modest cold, there seems to be no point in attempting to use non-biathlon ammo in extreme cold conditions. Such weather is rare here, it is unlikely I'll be able to test biathlon ammo in similar conditions to compare how it fares.
 
There's little doubt that the very cold temps across much of Ontario today does nothing to promote accuracy, for ammo and shooter alike. It's likely that in such cold temps affects unfavourably the the moisture that's naturally distributed in the bore as a result of shooting ammo. Rounds passing through frozen or nearly frozen fouling must be adversely affected.

How the lube itself is affected by cold temps is unclear, but it's probably not for the best. What is clear is that Lapua says the lube is the same on all its rimfire ammo, Biathlon included. The same is true for SK varieties with the same lube on all.

The key difference between Lapua standard rifle ammo and Polar Biathlon is the nominal MV (PB is a little faster) and the bullet shape. PB bullets are designed to facilitate chambering with the repeaters used in biathlon. Eley does the same thing by making the cartridge itself a little smaller in diameter than Eley standard rifle match ammo.
 
Leuchtkafer said:
Well, I was going to shoot an ORPS and NRL22 match today. I can report my experience of attempting to shoot in -30C, I withdrew after 2 rounds. Everything seemed fine at sight in, MV just 20fps slower than in normal temperature. I hit nothing in round 1, went back to the sighter board and had no idea what was going on... up for round 2, again a big fat 0. Back to the sighter board at 50 yards, I finally see two hits land, a full 2 Mil vertical between them, that's 3.6 inches. It was like my rifle became a smooth bore between sight in and round 1. Along with Fail-To-Fire malfunctions, next round slowly feeding up from the magazine, foggy glasses and freezing my gonads off, having zero accuracy sealed the deal, I was outta there.

Deductive reasoning suggests the interplay of extreme cold with the ammo lube and/or moisture in the bore from firing to be the cause of accuracy loss. I was shooting RWS Special Match. While petroleum based bullet lube may be usable in modest cold, there seems to be no point in attempting to use non-biathlon ammo in extreme cold conditions. Such weather is rare here, it is unlikely I'll be able to test biathlon ammo in similar conditions to compare how it fares.
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I mean -30 is pretty extreme. I stop after -10. Only because my joints seize up.
 
I'm generally unable to get the results I typically get below -20C. Even then things may be OK for a while but I won't get a complete two card session in. Carbon rings build much faster at those temperatures.

Leuchtkafer I must give a nod to your dedication.
 
With consistent ammo temps near freezing or below don't impair accuracy performance, as Williwaw and horseman2 indicate. Good lots of non-biathlon ammo still perform well. It's when temps become very cold that accuracy suffers regardless of ammo.
 
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