how temperatures affect reloading accuracy ?

RERICK · October 5, 2006, 02:52 PM

Its getting a little colder now where I live and I am starting to notice accuracy is suffering some on loads that normally would shoot well.For example cal 223 24 grains of Varget with a 60 grain VMAX Shoots super for me but at the range today it was around 55 outside and it shot kinda crappy.What gives and what can be done to make it better ?

amamnn · October 7, 2006, 12:10 AM

Many factors could be involved. My grandfather used to say: "never load in summer to shoot in winter." There are benchrest shooters who only load their ammo on the day of the match, at the range. Such extremes are debatable and have not been definitely proven to be any help in ensuring accuracy. We do know a few things for sure. When the weather is colder the air is denser and your bullets will fly differently, especially in the lesser B.C. of the small bores. Allowing your rifle time to acclimate will help. Leaving it out in the car overnight before going to the range is a good idea if you trust it will not be stolen. Loading your ammo far in advance does seem to have an effect on accuracy as the seasons change, so you might not want to load in big batches. The load that was grouping well in August may need a tiny bit more powder or be seated differently in October. A rifle that was free floating in the warm weather may be touching the stock during some shots in colder weather. If you have not mastered breath control you may find a difference in cold weather. It could be a combination of these factors and others which I failed to remember just now. I've not had much trouble with accuracy as the seasons change, but all the above have been put forward as causes and cures of such accuracy problems by people who are supposed to know the business.

MrGee · October 7, 2006, 09:31 AM

Great answer amamnn , but on another note back in the day we hunted upstate NY, an Ct. for deer, pretty cold up there in Nov. what we did for the cold months is actually dropped the powder charge an used magnum primers .. now living in NC even though the temp changes aren't so drastic, i see a change rather when the temp... rises above 85 .. varget being a good temperature tolerant powder is a good choice, an at 24grs. you still have room to increase as amamnn says....

mete · October 7, 2006, 12:19 PM

If you load maximum in the winter don't use these loads in the summer ,they'll be too hot !

RERICK · October 8, 2006, 09:10 AM

What about a faster powder such as H322 or H335 ?

amamnn · October 8, 2006, 10:08 PM

Sounds like a good workable idea, MrGee. Unfortunately my day was so far back we didn't have magnum primers. ----No cracks about spears, please.

castnblast · October 9, 2006, 10:51 AM

Another thought on this...If you load into the lands, ALL your components will shrink at colder temps. Theoretically, it should be the same, but it's not because you have different alloys/metals that shrink/expand at different rates. That is why I do not load my hunting rounds into the lands. I try to find a powder charge that will shoot well to standard COL measurements. That helps to cut down/eliminate a lot of that type of problem. Also, I use a bar scale, so I make sure to zero out my scale everytime I load. expansion/contraction effects them to, and it takes a much smaller temp change to make a difference on those scales.

It's also a good idea to practice shooting w/ your hunting clothes on. Heavy jackets and all. It's not like shooting from the bench, so don't expect the same patterns. I like to practice w/ my bipods and off hand at the range to see where my true limitations are. Seems to help.

30Cal · October 9, 2006, 03:08 PM

Varget doesn't vary much at all with temperature. I would suspect a shooter or rifle problem.

October 5, 2006, 02:52 PM	#1
RERICK Junior member Join Date: July 9, 2005 Posts: 369	how temperatures affect reloading accuracy ? Its getting a little colder now where I live and I am starting to notice accuracy is suffering some on loads that normally would shoot well.For example cal 223 24 grains of Varget with a 60 grain VMAX Shoots super for me but at the range today it was around 55 outside and it shot kinda crappy.What gives and what can be done to make it better ? Last edited by RERICK; October 5, 2006 at 06:26 PM.

October 7, 2006, 12:10 AM	#2
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	Many factors could be involved. My grandfather used to say: "never load in summer to shoot in winter." There are benchrest shooters who only load their ammo on the day of the match, at the range. Such extremes are debatable and have not been definitely proven to be any help in ensuring accuracy. We do know a few things for sure. When the weather is colder the air is denser and your bullets will fly differently, especially in the lesser B.C. of the small bores. Allowing your rifle time to acclimate will help. Leaving it out in the car overnight before going to the range is a good idea if you trust it will not be stolen. Loading your ammo far in advance does seem to have an effect on accuracy as the seasons change, so you might not want to load in big batches. The load that was grouping well in August may need a tiny bit more powder or be seated differently in October. A rifle that was free floating in the warm weather may be touching the stock during some shots in colder weather. If you have not mastered breath control you may find a difference in cold weather. It could be a combination of these factors and others which I failed to remember just now. I've not had much trouble with accuracy as the seasons change, but all the above have been put forward as causes and cures of such accuracy problems by people who are supposed to know the business. __________________ "If the enemy is in range, so are you." - Infantry Journal

October 8, 2006, 10:08 PM	#6
amamnn Senior Member Join Date: May 13, 2006 Location: WA, the left armpit of the USA Posts: 1,323	Sounds like a good workable idea, MrGee. Unfortunately my day was so far back we didn't have magnum primers. ----No cracks about spears, please. __________________ "If the enemy is in range, so are you." - Infantry Journal

October 9, 2006, 10:51 AM	#7
castnblast Senior Member Join Date: July 2, 2006 Location: Corpus Christi TX Posts: 1,148	Another thought on this...If you load into the lands, ALL your components will shrink at colder temps. Theoretically, it should be the same, but it's not because you have different alloys/metals that shrink/expand at different rates. That is why I do not load my hunting rounds into the lands. I try to find a powder charge that will shoot well to standard COL measurements. That helps to cut down/eliminate a lot of that type of problem. Also, I use a bar scale, so I make sure to zero out my scale everytime I load. expansion/contraction effects them to, and it takes a much smaller temp change to make a difference on those scales. It's also a good idea to practice shooting w/ your hunting clothes on. Heavy jackets and all. It's not like shooting from the bench, so don't expect the same patterns. I like to practice w/ my bipods and off hand at the range to see where my true limitations are. Seems to help. __________________ VEGETARIAN...old indian word for bad hunter

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October 7, 2006, 09:31 AM	#3
MrGee Senior Member Join Date: June 7, 2005 Location: NC Posts: 260	Great answer amamnn , but on another note back in the day we hunted upstate NY, an Ct. for deer, pretty cold up there in Nov. what we did for the cold months is actually dropped the powder charge an used magnum primers .. now living in NC even though the temp changes aren't so drastic, i see a change rather when the temp... rises above 85 .. varget being a good temperature tolerant powder is a good choice, an at 24grs. you still have room to increase as amamnn says....

October 7, 2006, 12:19 PM	#4
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	If you load maximum in the winter don't use these loads in the summer ,they'll be too hot !

October 8, 2006, 09:10 AM	#5
RERICK Junior member Join Date: July 9, 2005 Posts: 369	What about a faster powder such as H322 or H335 ?

October 9, 2006, 03:08 PM	#8
30Cal Senior Member Join Date: December 3, 2002 Posts: 1,264	Varget doesn't vary much at all with temperature. I would suspect a shooter or rifle problem.