I was able to make the range this morning for a few hours . It was very cold when I arrived with a temperature of 19 and wind chill around 10 or so . I have a pet loading for my AI Remington , that is good for around .4 to .6 for the most part when I do My job behind the trigger . I have read that Varget is a very temperature stable powder and for the most part has been my experience with it . I've seen loads get a little hot in midsummer , when the round sit in the sun , but still shot great . The first twenty down range , the groups opened up into two distinct groups side by side , stringing slightly vertically opening up to ~ 1.2 - 1.5 inches slowly getting tighter as I progressed . The second twenty tightened up significantly , into about normal group size for this piece . It did warm up significantly for the second target sets , into the thirty's . What are your experiences , was it just the loose nut behind the trigger shivering , or do I need to step up the loading a bit for the very cold . Any thoughts ?
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Re: Cold Weather : Effect On Your Loads ?
I had similar questions resulting from my experience at the range on Saturday. In fact I was going to start a thread on it until I saw yours already posted.
Started when temp was in the high 30's to low 40's. Beginning muzzle velocities were reading 100-130 fps lower than I expected (from past summer readings). As the morning progressed, the air temperature increased 10 to 15 degrees (ammo temp may have increased even more sitting in the sun). By the end, I saw an increase in my Chrono velocities by 25 to 30ish fps (I'll need to go home and look at my records for an exact number). I was shocked. I didn't think Varget was that sensitive to temperature. I don't know if my chrono was off or if Varget really does vary that much.
What are your thoughts? Is this normal, or do I need to get my chrono recalibrated or replaced?
I had similar questions resulting from my experience at the range on Saturday. In fact I was going to start a thread on it until I saw yours already posted.
Started when temp was in the high 30's to low 40's. Beginning muzzle velocities were reading 100-130 fps lower than I expected (from past summer readings). As the morning progressed, the air temperature increased 10 to 15 degrees (ammo temp may have increased even more sitting in the sun). By the end, I saw an increase in my Chrono velocities by 25 to 30ish fps (I'll need to go home and look at my records for an exact number). I was shocked. I didn't think Varget was that sensitive to temperature. I don't know if my chrono was off or if Varget really does vary that much.
What are your thoughts? Is this normal, or do I need to get my chrono recalibrated or replaced?
Re: Cold Weather : Effect On Your Loads ?
this might help
http://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3023140#Post3023140
this might help
http://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3023140#Post3023140
Re: Cold Weather : Effect On Your Loads ?
Different lighting conditions can produce different chrono readings, especially with a cheaper brand of chrono, but they are all subject to it. It's a photo sensor that depends on light to work. At some point it reads what you expect it to read, and at some point it doesn't read at all. It's perfectly probable then that between those two points it reads differently. As your morning progressed; and as the temperature increase; so did the position of the sun and the condition of the sky, change.
In most cases, for the type of shooting I do, developing a load with the OCW principles installs enough plus/minus tolerance to negate much of what is often deemed by the unknowing as "temperature sensitivity". True, some powders by their own burn characteristics are less "sensitive" than others, but OCW takes a LOT of the variance out of the powders that some people are quick to call too temp sensitive.
On a side note: it's NEVER smart to leave ammo in the direct sunlight regardless of the conditions or circumstances. It's too easy to just keep it in the shade.
Different lighting conditions can produce different chrono readings, especially with a cheaper brand of chrono, but they are all subject to it. It's a photo sensor that depends on light to work. At some point it reads what you expect it to read, and at some point it doesn't read at all. It's perfectly probable then that between those two points it reads differently. As your morning progressed; and as the temperature increase; so did the position of the sun and the condition of the sky, change.
In most cases, for the type of shooting I do, developing a load with the OCW principles installs enough plus/minus tolerance to negate much of what is often deemed by the unknowing as "temperature sensitivity". True, some powders by their own burn characteristics are less "sensitive" than others, but OCW takes a LOT of the variance out of the powders that some people are quick to call too temp sensitive.
On a side note: it's NEVER smart to leave ammo in the direct sunlight regardless of the conditions or circumstances. It's too easy to just keep it in the shade.
Re: Cold Weather : Effect On Your Loads ?
I have used the same load of varget in temperatures ranging from upper 20s to triple digits and have not noticed any real change in p.o.i. or velocity. The most extreme spread we get here in Texas is about 90 degrees. That is nothing compared to the difference in chamber temperatures from the first cold bore shot to the last round in a long string of fire. Other factors may be how long the round sits in a hot chamber or if your bedding changes with temperature. I really dont think about it much anymore as it doesnt seem to make any difference in what I do.
I have used the same load of varget in temperatures ranging from upper 20s to triple digits and have not noticed any real change in p.o.i. or velocity. The most extreme spread we get here in Texas is about 90 degrees. That is nothing compared to the difference in chamber temperatures from the first cold bore shot to the last round in a long string of fire. Other factors may be how long the round sits in a hot chamber or if your bedding changes with temperature. I really dont think about it much anymore as it doesnt seem to make any difference in what I do.
Re: Cold Weather : Effect On Your Loads ?
I have a question that kind of follows these lines... "How cold is too cold?" I want to test some loads this weekend, the forecast is saying -18C (-1F). Would this be "too cold" to test? I know I can handle it, I'm Canadian, after all...
I have a question that kind of follows these lines... "How cold is too cold?" I want to test some loads this weekend, the forecast is saying -18C (-1F). Would this be "too cold" to test? I know I can handle it, I'm Canadian, after all...
Re: Cold Weather : Effect On Your Loads ?
Check this out for ocw testing.http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134
You should read this too. http://www.6mmbr.com/laddertest.html
As far as the value of the results you got, that depends on the conditions you will be using the load. I like to work up a coyote load this time of year because these are the conditions I will b using it. If you want a load for year round use develop it during the summer so you won't risk increased pressures as the weather warms up.
Check this out for ocw testing.http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134
You should read this too. http://www.6mmbr.com/laddertest.html
As far as the value of the results you got, that depends on the conditions you will be using the load. I like to work up a coyote load this time of year because these are the conditions I will b using it. If you want a load for year round use develop it during the summer so you won't risk increased pressures as the weather warms up.
Re: Cold Weather : Effect On Your Loads ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: McGuyver</div><div class="ubbcode-body">Thanks Tripwire. Quick question: what is the OCW method of load development?
I guess most of my data from Saturday is suspect then and should probably be discarded? That's frustrating.
</div></div>
Bad data is just as valuable as good data....think about it.
Optimal Charge Weight, lot's of folks use it, I live by it.
It's a load method that addresses the barrel harmonics so that they have the least influence on the bullet launch by timing the exit of the bullet at an optimal point in time. Pretty simple really, once you gain an understanding of how it works.
Read this.....http://optimalchargeweight.embarqspace.com
Then join this site and talk to Newberry himself about it.....
http://practicalrifler.6.forumer.com
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: McGuyver</div><div class="ubbcode-body">Thanks Tripwire. Quick question: what is the OCW method of load development?
I guess most of my data from Saturday is suspect then and should probably be discarded? That's frustrating.
Bad data is just as valuable as good data....think about it.
Optimal Charge Weight, lot's of folks use it, I live by it.
It's a load method that addresses the barrel harmonics so that they have the least influence on the bullet launch by timing the exit of the bullet at an optimal point in time. Pretty simple really, once you gain an understanding of how it works.
Read this.....http://optimalchargeweight.embarqspace.com
Then join this site and talk to Newberry himself about it.....
http://practicalrifler.6.forumer.com
Re: Cold Weather : Effect On Your Loads ?
Thanks to all for the input on the subject . I wouldn't think that a max 20 feet per second difference would make much of a difference . I'm sure there are other factors at play with the issue ; ie barrel temp and harmonics , air densities , primer ignition . Thanks for the links , lots of good stuff to absorb
Thanks to all for the input on the subject . I wouldn't think that a max 20 feet per second difference would make much of a difference . I'm sure there are other factors at play with the issue ; ie barrel temp and harmonics , air densities , primer ignition . Thanks for the links , lots of good stuff to absorb
Re: Cold Weather : Effect On Your Loads ?
Here is a writeup on configuring quickload with the optimal barrel time concept which I believe is similar or the same thing as optimal charge weight. Basically if you get enough data into quickload it can tell you which charges will be your optimal nodes because it knows when the projectile will be exiting the barrel. I have used it once so far. I already had done all the work to find an optimal load for my particular rifle and and after I got all the data into quickload the answer it gave me was the same load. I plan on using it again when my new barreled actions get back form the smith.
The one thing that takes some work is collecting specific accurate burn data about your powder. The data changes batch to batch and quickload comes with data that is just in the ballpark. Could be off by up to 20%. For that reason you are well served buying a few kegs from the same lot and doing the work once.
http://www.the-long-family.com/optimal%20barrel%20time.htm
Here is a writeup on configuring quickload with the optimal barrel time concept which I believe is similar or the same thing as optimal charge weight. Basically if you get enough data into quickload it can tell you which charges will be your optimal nodes because it knows when the projectile will be exiting the barrel. I have used it once so far. I already had done all the work to find an optimal load for my particular rifle and and after I got all the data into quickload the answer it gave me was the same load. I plan on using it again when my new barreled actions get back form the smith.
The one thing that takes some work is collecting specific accurate burn data about your powder. The data changes batch to batch and quickload comes with data that is just in the ballpark. Could be off by up to 20%. For that reason you are well served buying a few kegs from the same lot and doing the work once.
http://www.the-long-family.com/optimal%20barrel%20time.htm
