I live in Alaska and have quit developing any loads when it's blow 20F. In the last couple of years, I was using the 10 shot ladder method (Satterlee) and started having issues with accuracy when temps got 50F and above. For all of these loads but one, I used Hodgdon Extreme powders as well. While I wasn't seeing my loads open up 2-3 times what they were, they did open up some. I could go from a 1" (3 or 5 shot group) to a 1.5" group when temps warmed up. I have moved on to more of an OCW type of load testing and my issues seem to have gone away.
Accuracy lost on warmer weather
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I am a varmint hunter. Fox and coyotes in the snow in Minnesota. Always cold, sometimes very cold.
Cold bore shots are very imortant to me as they are few and far between. They are usually beteen 600 and 1200 yards. I wanted to learn preccision. I needed to find out who knew relaoding and etreme acccuraccy. The NBRSA is basicly the spearhead of precision shooting. So after hearing about nbrsa I decided to shoot NBRSA 100-200 beacuse I wanted to learn. The first thing I learned is load development changes from morning to evvening. Tempurature, wet bulb, humidity etc. Yes to your question. you need a summer load and a winter load. It effects your groups dramatically. I am waiting for late fall so I can tune for winter fur harvest. I wont waste my time, components and barrel life just to satisfy a need to shoot. So now I shoot a summer rifle (6PPC) and wait for the snow to tune my fur rifle.
good luck brother, hope you find a good summer load
Cold bore shots are very imortant to me as they are few and far between. They are usually beteen 600 and 1200 yards. I wanted to learn preccision. I needed to find out who knew relaoding and etreme acccuraccy. The NBRSA is basicly the spearhead of precision shooting. So after hearing about nbrsa I decided to shoot NBRSA 100-200 beacuse I wanted to learn. The first thing I learned is load development changes from morning to evvening. Tempurature, wet bulb, humidity etc. Yes to your question. you need a summer load and a winter load. It effects your groups dramatically. I am waiting for late fall so I can tune for winter fur harvest. I wont waste my time, components and barrel life just to satisfy a need to shoot. So now I shoot a summer rifle (6PPC) and wait for the snow to tune my fur rifle.
good luck brother, hope you find a good summer load
Aled24
Member
What nobody has mentioned is the fact that the barrel itself is getting hot just sitting in the sun without a single shot fired, the thinner your barrel the quicker it gets hot especially a blued barrel.
I would make a summer and winter load or choose a more stable powder,
Also if you have extreme temperatures variation even the action screws torque settings could make a difference.
I would make a summer and winter load or choose a more stable powder,
Also if you have extreme temperatures variation even the action screws torque settings could make a difference.
hunterbob
Well-Known Member
I'm saying you just had a bad day shooting. I had the same thing happen at times.
I have not heard of this for many years. Back in the day, before all of the fancy stock materials, glass bedding, free floating barrels and what have you these days it was not uncommon for a rifle to react differently to cold, heat, dry air, damp air and the list goes on. There were a lot of issues if a hunter went out and sighted in his rifle during the warm weather then went hunting in cold weather only to miss an easy shot and not know why, until a shot was taken at an impromptu target out in the woods only to find that the rifle was not hitting anywhere close to where it was sighted in during the warmer weather.
In the post above you did not mention what kind of rifle, what kind of stock, is it glass bedded? Is it pillar bedded, is the barrel floated and did you check to make sure that the barrel was not coming into contact with the stock. Are the bedding screws torqued properly? Is it a wood or synthetic stock. If wood what kind of wood?
People who were not around many years ago, or never had older firearms with wood, because that was all there was at the time stocks that played all kinds of games on rifle accuracy. Wood expands and contracts with temperature changes. It absorbs moisture as well as looses moisture. The barrel channel will twist in different directions due to the grain of the wood which can cause all kinds of accuracy issues.
OK, so it's a synthetic or even metal stock. Synthetics as well as metal might not have the issue with moisture or warping they still are affected by temperature. Torque your action screws in 80 degree weather, then cold soak the rifle in zero degree weather and you will find that the torque on the action screws is nowhere near specified torque because the materials have all shrunk due to the cold and everything is now loose and moving slightly with each shot which affects the zero.
Another thing is the 1/12 barrel twist rate. That seems like an awful slow twist even for a 53 grain bullet. The twist rate on most .223 rifles is anywhere between 1/10 and 1/7 depending on the weight of the bullet to be fired. I have two MSR's one with a 1/9 twist, the other with a 1/7 twist. The 1/9 will not shoot a 55 gr bullet but will a 62 gr bullet. The 1/7 won't shoot anything less than a 69 gr but loves 75 and 77 gr bullets. Why yours shoots good in warm weather but not so good in cold weather can and often is caused by the difference in muzzle velocity and powder that despite manufacturer's claims is more sensitive to cold than they care to admit. Use a chrono to check the real velocity when the rifle is shooting good when it's warm out, then check it when its not shooting so good. The difference might be surprising.
As a final thought, you might want to check the rifles zero and re-zero it in cold weather instead of warm weather. We all used to do this many years ago before the fancy ammo and powders claiming to not be affected by temperature. So with all of the above now in mind what are your thoughts on which of the above are causing your problem?
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That bullet needs an 8 twist or faster. I've used the Bison Ballistics APP and it's been pretty good in defining weight/length of bullet to twist of barrel and speed needed for best accuracy.
I need to run some stuff through one of these calculators. The standard twist on a 22-250 is 12 and they shoot bullets to 65 grains just fine. The standard twist on a 22 hornet is 16. The Hornet shoots 50 grain bullets just fine and at 2600 fps. I cannot conceive of why a 12 223 can't stabilize a 53 grain bullet at 3200 to 3300 fps.
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It states "The bullet is unstable in this configuration, and will tumble. A faster twist is required under these conditions."
Go to their website and plug in your parameters. I get most of the bullet lengths from JBM Ballistics.
M1A1ABRAMS
Well-Known Member
He mentioned it was a Boyds stock n bedded.
Joe-boy
Well-Known Member
It's a pillar and glass bedded laminate stock with very sufficient clearance between the barrel and the stock. The world is full of guns that work just fine with this setting so I'm having a hard time to think guns couldn't work with pillar bedded laminate stocks. Also worth mentioning it has a varmint barrel.In the post above you did not mention what kind of rifle, what kind of stock, is it glass bedded? Is it pillar bedded, is the barrel floated and did you check to make sure that the barrel was not coming into contact with the stock. Are the bedding screws torqued properly? Is it a wood or synthetic stock. If wood what kind of wood?
Another thing is the 1/12 barrel twist rate. That seems like an awful slow twist even for a 53 grain bullet. The twist rate on most .223 rifles is anywhere between 1/10 and 1/7 depending on the weight of the bullet to be fired. I have two MSR's one with a 1/9 twist, the other with a 1/7 twist. The 1/9 will not shoot a 55 gr bullet but will a 62 gr bullet. The 1/7 won't shoot anything less than a 69 gr but loves 75 and 77 gr bullets. Why yours shoots good in warm weather but not so good in cold weather can and often is caused by the difference in muzzle velocity and powder that despite manufacturer's claims is more sensitive to cold than they care to admit. Use a chrono to check the real velocity when the rifle is shooting good when it's warm out, then check it when its not shooting so good. The difference might be surprising.
As a final thought, you might want to check the rifles zero and re-zero it in cold weather instead of warm weather. We all used to do this many years ago before the fancy ammo and powders claiming to not be affected by temperature. So with all of the above now in mind what are your thoughts on which of the above are causing your problem?
12 twist for 223 has been around for ages and is widely used. It sure does limit the length/weight of the bullets to be used, but there are millions of guns that shoot just fine with the 12 twist. Also at least brownells states the 53 grain vmax should work with 12 twist. Also the stability should be better in hotter climate, not worse. On the other hand, when things were working it was a 100 m range, this time it was 150 meters. The 53 grain vmax is a long bullet for its weight and the stability depends on the length of the bullet, not the weight, so some heavier bullets may actually be even shorter if they are blunt nose and flat base.
The zero was just fine, it's the grouping that sucks. Or well, difficult to say if it's half an inch this or that way when the group is all over the place, but no significant zero change.
Thank you all for the comments. I still think the two best guesses are
1)Something weird with the stability, maybe starting to lose the stability after 100 meters. I know the stability of the bullet with 12 twist could be better but as mentioned, it has grouped just fine in colder weather
2)The barrel harmonics node is super narrow which causes the load to "exit the node" when the temperature changes.
The poor grouping was consistent and repeatable while I was shooting way better with other loads.
I'll try the freezer trick next time I go to the range and report back. There's a risk we might learn something from this
Way easier than freezing the bullets, just run the loads over a chronograph. My odds on bet is you are getting way more velocity hot and this is what is buggering up the groups. That is the place to start. All the other stuff that can be looked at comes AFTER you know what the load is doing at the different temperatures. The odds of the bullet being less stable in hotter weather are zero.It's a pillar and glass bedded laminate stock with very sufficient clearance between the barrel and the stock. The world is full of guns that work just fine with this setting so I'm having a hard time to think guns couldn't work with pillar bedded laminate stocks. Also worth mentioning it has a varmint barrel.
12 twist for 223 has been around for ages and is widely used. It sure does limit the length/weight of the bullets to be used, but there are millions of guns that shoot just fine with the 12 twist. Also at least brownells states the 53 grain vmax should work with 12 twist. Also the stability should be better in hotter climate, not worse. On the other hand, when things were working it was a 100 m range, this time it was 150 meters. The 53 grain vmax is a long bullet for its weight and the stability depends on the length of the bullet, not the weight, so some heavier bullets may actually be even shorter if they are blunt nose and flat base.
The zero was just fine, it's the grouping that sucks. Or well, difficult to say if it's half an inch this or that way when the group is all over the place, but no significant zero change.
Thank you all for the comments. I still think the two best guesses are
1)Something weird with the stability, maybe starting to lose the stability after 100 meters. I know the stability of the bullet with 12 twist could be better but as mentioned, it has grouped just fine in colder weather
2)The barrel harmonics node is super narrow which causes the load to "exit the node" when the temperature changes.
The poor grouping was consistent and repeatable while I was shooting way better with other loads.
I'll try the freezer trick next time I go to the range and report back. There's a risk we might learn something from this
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Joe-boy
Well-Known Member
Good point. I'll try to take a chrono with me. It's not a fancy and accurate one, but with a large enough sample size probably can tell the difference.
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Is it possible your scope or muzzle crown has been damaged in the time between shooting in cold and hot weather? Just another thought.
Joe-boy
Well-Known Member
Don't think so. I use a silencer which protects the crown and some other loads I shot, such as the 52-grain Nosler Custom Competition, shoot just fine. Also the rifle has not seen any rough use.
I'll chrono the loads in hot ambient temp and from freezer, shoot these to two different targets, and report back.
