How does cold affect your barrel?

[Timberman]

I've noticed over the last couple of years that a rifle I had sighted in during hot humid weather(July 90 deg,90% humidity) will be off at ranges past 250 yards when shooting in 20 to 30 degree weather. Not very consistently either. Anyone else had this happen?

 

[Shawn Carlock]

Everyone will experience some shifting due to different weather changes. You will start to shoot lower as the temp and humidity drop. Also depending on powder, load, etc. you may be shooting slower at the muzzle in cooler temps. Drops in velocity can also change point of impact for windage also but tend not to be as much as elevation. Also do you change physical elevation by going to your hunting area? These conditions all make a difference at distance.

 

[Timberman]

That's what happens, it drops more. Quite a bit, really. I'm still at the same elevation, maybe 3 feet above sea level. Around here the highest point within 60 miles or so is the highway overpass. Maybe the landfill. I guess I'll have to shoot it on paper in the cold weather sometime, it just adds to the confusion to have a different set of numbers to go by.

Also meant to ask, is it the air itself creating these condiitons, or the barrel temp.? Would keeping the gun in the truck all week be better than taking it in the house at night, or putting handwarmers in the gun case while in the field help anything? Just curious.

 

[Kevin]

It is mainly the air that is doing it. In the cold, air is much more dense. Your initial velocity (depending on powder) could be lower as well. Barrels in general shoot worse groups in the cold also.

The benefit to leaving your gun in the truck would be that condensation will not get all over it when you bring it in the warm house. For this same reason I would not reccomend the handwarmer idea. If the gun was in the cold and then putting it in a warm gun case would form condensation on the gun.

 

[Buffalobob]

Take the gun in the house so it doesn't get stolen.

If you can keep some bullets in an inside shirt pocket where the powder will be up near body temperature then that will help on keeping up muzzle velocity. If you get the opportunity for a long range shot then just take out your cold cartridge and slip in a warm one.

For the first time in thirty something years I will miss opening day. Family obligations are just more important than chasing deer this Saturday.

Good luck to you.

 

[Timberman]

10-4 on the condensation deal. I'll just keep the ammo in my shirt pocket and the gun & case in the garage. I'm also going to limit my shots to 300, until I get a better handle on the cold weather ballistics. I blew the front legs off a nice deer 2 years ago, at 415 yards, and I was aiming at center of the shoulder. Had to get up and run all the way down there (coveralls/coat/boots, huffing & puffing). Don't want to make that mistake again. Sorry you can't go tomorrow buffalobob, but family does come first. Gotta do what you gotta do.

 

[davewilson]

i've seen a lot of guys come in to camp when it was fairly cold and have their guns shoot high.in fact i would say way more shoot high in cold weather than low.has nothing to do with the air but the stock can push up on the barrel.i always told the guys to put their gun and ammo in the freezer for 2 days,yes 2 days,then see where it will print.the added bonus with this is you get to see if the gun will even go off when it gets cold.

 

[Shawn Carlock]

Timberman,

Most of the issues you are facing come from the flight of the bullet in the different air conditions. Remember that if TEMP, ELEVATION, OR HUMIDITY go down so does the point of impact. I would also chronograph your loads in cold temp to see if the muzzle velocity is effected.

 

[davewilson]

Shawn, i respectfully disagree with your statement.when the temp goes down, so does your point of impact.it's just not that simple.i have seen dozens of guns shoot higher when it was colder out.even if the velocity of the bullet is less,that alone could make it print higher.

 

[Mysticplayer]

Changing weather can affect the stock and the action bedding. Why I prefer lam, synthetic or composite stocks. Also, I leave quite a large gap around the barrel and stock so any shift is not going to hit the barrel.

Most powders will 'lose' velocity as temp drops. This will affect trajectory but more importantly, barrel tuning as the load has effectively changed. Like using less powder in the summer.

To solve this, I shoot Hodgdon Extreme powders. These are very temp stable and shoot essentially the same from the summer to mild winter (I don't hunt when it gets really cold - season ends before that). There are a few other companies now making stable powders. Definitely do your research.

For primers, I use the CCI BR2 and Fed 210M for stand cases and the Fed 215M for magnum cases. They all seem to ignite very consistently in varying temperatures.

I do alot of shooting in the warmer months and test in early fall/winter just to make sure all is well. By using a stable stock and stable ammo, I have found almost no change in POI and drop tables.

You could of course work up a cold temp load and test/use only in the winter. That's more of a pain then I like. Plus are very real danger of using a cold load in the summer and locking things up.

I have only experienced once when the barrel itself changed POI due to extreme cold. This was definitely bitterly cold (around minus 10C and no fun to shoot in). After a few shots and the barrel went back to the 'normal' POI. The ammo worked well even with these cold temps.

Testing is the only way to know for sure...

Jerry

 

[jro45]

Where I live I sight my rifle in when it get gets cold and the air thins. Like when you have to wear a jacket. I resight it in again in the summer time like when my rifle doesn't shot to point of aim. What I do is make sure my rifle that I'll be using is sighted in before I leave on a hunting trip to what ever the temperture is outside. This works for me. /ubbthreads/images/graemlins/smile.gif

 

[Michael Eichele]

I do a great deal of shooting in both 60-80 degree air as well as sub zero air close to sea level. If my ammo is kept in a warm truck around 70 degrees I dont notice a zero or accuracy change out to 300 yards. 400-600 is small and after 600 yards its time to really compensate for the thick air. I only use McMillan stocks to minimize the cold air's effect on my rifle. I am VERY lucky to have a 308 that will not throw bullet #1 out of the group due to the "cold bore" shot. Even if the barrel has been in -10 degrees for quite some time. This is of course if I am using warm ammo. If your ammo is going to get that cold, its best to develop a load for your hunt in those conditions. Personaly I tend to keep ammo in my pocket and load the rifle when I am setting up for the shot.

Some key points to think about in cold air shooting:

Use a GOOD synthetic stock free floated.

Keep the barrel to 26" or less. including brakes.

Keep your ammo warm or develop for the enviornment and/or use only EXTREEM powders or learn in detail what happens to you velocity at various temps, then compensate for your POI and trajectory accordingly.

If your rifle has a cold bore issue, concider a warm up shot followed by the killing shot. You will not need to use this practice up to 300 yards unless you have a real turd of a rifle.

 

[Bud Meadows]

A rule of thumb I was taught when I shot for the All-Army Rifle Team back in the early 1970's was one MOA change for every 15 degrees of temperature change. Thus, if you zeroed your rifle at 60 degrees and then later shot it in 15 degree weather, you'd be 3 MOA low. Of course, this was shooting Lake City Match ammo in Match Grade M-14's. I still shoot Lake City Match .308 ammo in my Ruger 77V, and find this rule of thumb is still pretty accurate.

 

[jeeper1]

I know guys when shooting their hunting rifles in the summer they keep the ammo in a cooler on ice.