change in POI with frigid temps

[steven gordon]

Took two of my three savage 10MLII's (I don't have a problem, I can quit anytime I want. I just don't want to quit right now.) out today to sight in. They both hit 3" high at 100 yards; I fiddled the sights a little bit and they're printing in the little circle just fine.

The thing is that the last time I sighted them in it was about forty degrees and today it was about 0 degrees. Is it the temp difference, and if so, do I compensate when it warms up? If not, can I attribute it to just neglecting the rifles for most of the summer and fall, not to mention spring?

I'm using 43 grains of XMR with power belt bullets. Yeah, it's overkill on the size white tail does I take. It's overkill on any whitetail bucks in the state, and it's overkill on elk. It's probably overkill on buffalo.

I leave the bears alone.

[kt]

interesting, i posed the same question a year or two ago. i have an omega which i shoot all summer and it is always 1.5" high at 50 , 0 at 100, the gun is a tack driver on the range however, late in the first year i had it, the temp was 5 degrees with a 20mph chill, just for fun i walked down an old road to find a doe bedded in cut corn, laying on the ground shooting off my book bag when she stood she was un harmed until i chased her down and got off a 10 yard shot at the other end of the field. earlier this year in our ML season i missed a deer in a similar set up, what gives? i dont know so i took it to the range on a mild day in november and low and behold it is still on the same zero from day one! so i believe some people here noticed a difference most didnt. i shoot pyro pellets and some body recommended i switch to loose black powder, i regret to inform you that this is a recommendation i have not tried
kt

[rattus58]

Temperature changes affect everything in life, including shooting. The air is way more dense for one thing when it gets frigid, thus causing more aerodynamic drag on the bullet in all phases.

Pressure goes up I'm told in the barrel too, when it gets cold and bullet drag could also be increased with frigid temperatures.

As for bullets hitting high when cold, it could be because of the barrel time theory at work. The theory goes....:

When a bullet leaves the barrel, it travels at X velocity which equates to Y time in the barrel. The barrel imparts a muzzle lifting (muzzle flip) with each shot and if you have a bullet that stays in the barrel longer, it will exit at a higher point in the arc than will a bullet going faster.

Therefore, with your warmer bullet barrel time (faster), the bullet leaves the barrel at a lower point in the "flip". When it froze up, the bullet is going slower and therefore exiting at a higher point in the muzzle flip (arc) and is therefore hitting the target at a higher point of impact.

If you have screwed your barrel to a heavy table that allows for sliding back of the rifle on bearings etc, this probably wont work in theory and your bullets will hit low.

Aloha... Tom