Cold weather

Snoepie

Snoepie

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I understand that cold weather affects gun powders and your MV will normally be slower.

However, all my hunting rifles are fitted with wooden stocks (as opposed to synthetic stocks) and I was wondering if cold weather can also affect the rifle as such and cause your point of impact to change to the extent that you entirely miss a deer at 100 yards?

If so, would your only solution be to sight your rifle in at lower temperatures?

Your advice would be appreciated
 
Probably not a complete miss at 100. A wounding shot is possible though. You should seal the barrel channel and the receiver if you haven't glass bedded it. Any wood sealer from any hardware store will do. Keeps moisture out of the wood and prevents swelling.
In extreme cold, any oil and/or grease will harden and possibly cause your rifle to fail to fire as well. Shoot 'em bone dry or lubed with powered graphite. There are greases made for the cold too. They're not cheap.
 
100 yds shouldnt be a worry depending on the caliber. Best to sight in at some reasonable cold temperature though and see for yourself.
If you load - use temp stable powders like the Extreme Hodgdons- Varget is very stable for example
I find the Reloader series 15, 19, 22 to be relatively stable.
At -40 you will still find some difference with stable powders to plus 40 degrees. The longer the distance, the more important it becomes of course. You have to test in the climate that you shoot in - its the only way you will now for sure
 
Ive read a atircle in the Accurate Rifle that states primers are more effected than powder at colder temperatures. The article was really heavy stuff, written by M.L. McPherson. I agree that Extreme Hodgdons and Varget + Allaiant powders do well. Know as for bullet impact changes according to tempurature that is more likely due to atmospheric conditions such as air density(barometric pressure), thiner air when cold. Thus the bullet flys with less resistance. Also I have read that a 20 degrees in temperature will change POI by one MOA. The same being said for changes in alltitude, 1000 feet for 1 MOA:runaway:
 
High velocity loads seem to suffer more than moderate velocity loads when it gets cold. If your velocity drops off due to the cold, it is difficult to say how that might change your POI at any given range, but suffice to say it would be equivalent to firing a lighter charge in warm weather. This has an impact on barrel harmonics, particularly with long light barrels, so could result in significant changes in windage as well trajectory if you were sighted in at +20 C and the next time you shot was at -45 C.

There are a few things you can do to mitigate matters. The first is to choose what is often referred to temperature stable powders. These are most often designed for stability in warm temperatures rather than cold, because high pressure in the heat can be dangerous, but you may find it helps. I've been having some success with Hybrid 100V from Hodgdon. H 100V is made in the US and formulated for temperature stability at -40, although I am not sure that their testing is pertinent to a propellant for small arms. The most important thing you can do is to shoot the rifle throughout the year, and keep records of the loads performance under a variety of conditions and locations. Changes in elevation will also effect your POI. If your rifle was sighted a couple of inches high in the summer, but in the winter you found it hit point of aim at 9:00, you can then anticipate the change and correct for it.
 
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7 num num said:
Ive read a atircle in the Accurate Rifle that states primers are more effected than powder at colder temperatures. The article was really heavy stuff, written by M.L. McPherson. I agree that Extreme Hodgdons and Varget + Allaiant powders do well. Know as for bullet impact changes according to tempurature that is more likely due to atmospheric conditions such as air density(barometric pressure), thiner air when cold. Thus the bullet flys with less resistance. Also I have read that a 20 degrees in temperature will change POI by one MOA. The same being said for changes in alltitude, 1000 feet for 1 MOA:runaway:
Click to expand...

Actually colder air is more dense. This may increase drag.

Regards,
 
The calibre, primer, load, air density nor anything else doesn't make a lick of difference if a wooden stock swells from moisture. The POI will change.
 
sunray said:
The calibre, primer, load, air density nor anything else doesn't make a lick of difference if a wooden stock swells from moisture. The POI will change.
Click to expand...

We are talking about shooting in COLD weather, where it is DRY COLD. There is very little moisture in the air when it gets down to -20 and lower.

Hogden states that their Extreme powders show a less variationwith temperature changes. I don't think they tried to develope it that way it just happened with the formula. It still will have less pressure in the cold, just less drop than other powders. In my experience, ball powders such as win 748 is much more effected by cold and heat. I've seen 100+ fps drop in 30 deg. temp change. Exception is Ramshot TAC, it acts like the Hogden extremes. Since it does not get much hotter than 20 deg in hunting season, don't have to worry about the other extreme.
By the way, if you lube your guns, use G96 Gun Treatment, not grease of any kind.
 
It is hard to imagine cold weather causing a problem at 100 yards on a deer sized target.

But if the bolt / firing pin is oiled, the rifle might not fire. THAT is a problem.

A pilot will tell you that air density is a real issue between July and January. I have taken off from Toronto with 3 big guys in the plane, with scuba gear and plane was like a rocket. In Ft. Lauderdale, same plane barely cleared the houses at the end of a long runway. less lift, less engine h.p. and less prop thrust.
 
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