reloading in the cold

[223nut]

So I'm going to reload a batch of 338 lapua but I got thanking that the last batch was loaded at 75 degrees, and this one will be loaded in a un heated shop at about 40 degrees,

my load is lapua brass, fgm primers, h1000 powder, 300gr smk,

So is the lower temperature going to affect accuracy on my new batch?

 

[excaliber]

Re: reloading in the cold

Velocity will change with different temps. The powder you are using is Extreme which doesn`t change as much as other powders that isn`t. When you change velocity, your node also changes, so your accuracy might get better or worse.

 

[Early Cuyler]

Re: reloading in the cold

Temperature does affect burn rates and thus velocities. However some powders are less susceptible to this. I believe Hodgdon does a good job in making their powder less temp sensitive.

I doubt the temperature of your powder during reloading will have much effect (if any) in comparison to the temperature of your loaded rounds before firing.

 

[TexIndian]

Re: reloading in the cold

Ditto. I can't imagine temps when loading could be a factor. Temps when shooting is another question.

 

[Greg Langelius *]

Re: reloading in the cold

If you can stand the temperature without gloves <span style="font-style: italic">while handloading</span>, I seriously doubt the load will differ in any noticeable manner.

Temperature varitions while firing/between firing sessions can affect bullet flight, and ammunition temperatures (like rounds sitting in a hot chamber) can affect load performance.

My handloading facility is in an unheated garage, and temps up here close to Canada are dipping below frost at night. Soon, they'll only come up above briefly, so my handloading season is drawing to a close.

For the interim months, I'll be indoors; staying warm and fuilding rubber powered flying model airplanes.

Greg

 

[223nut]

Re: reloading in the cold

Ok, thanks guys.

 

[turbo54]

Re: reloading in the cold

The only reasons a change in temperature while loading might be of concern are:

1. Your scale, and therefore your charge weight.
2. Humidity, and therefore your effective charge weight.

My advice:

Get your scale warmed up and running nice, whether electronic or mechanical... Take a coin that weighs more than your charge weight, and start cutting/filing it down until it weighs EXACTLY what your charge weight does.

Now you have a customized check weight for your scale, to test it specifically tuned to THE WEIGHT you care about.

For me, with my 308, the magic weight is 45.5gr, which is about 95% of a penny.

I keep my test weight in a ziplock baggie with a little silica packet to keep corrosion away. I pull it out and check my scale occasionally.

To handle the humidity situation, the only advice I can offer is to keep a nice big dessicant pack in the bottle/jug of powder at all times, and to return unused powder to the jug as soon as your loading session is over. This method should keep your powder at a very low moisture content all the time, regardless of season.

Good luck.

 

[High Binder]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Take a coin that weighs more than your charge weight, and start cutting/filing it down until it weighs EXACTLY what your charge weight does.
</div></div>

Awesome idea!

 

[TexIndian]

Re: reloading in the cold

Re: the humidity issue, I have read before about powders 'absorbing' humidity and getting heavier than when the exact same powder was weighed before being exposed to the higher humidity. But I would imagine the powder has to be exposed to the humidity for quite a while before this happens - longer than a typical loading session anyway - and that we'd have to be talking about really high humidities. Seems more like a storage issue than a loading issue.

BTW, nice idea about making a test weight.

 

[Greg Langelius *]

Re: reloading in the cold

Well, I gotta admire the coin trick.

I once built a pretty big balance beam scale for weighing indoor rubber power model aircraft components. Entire aircraft can often weigh less than a penny. For reference weights I started with 8cc of water, and balanced it with a coil of copper wire. Cutting the wire into eight equal segments produced precise 1gm reference weights (1cc of water = 1gm).

For my version of the above, I'd skip the coin and use a length of solder wire. Probably easier and maybe even cheaper, but I'm not sure.

Greg

 

[vinconco]

Re: reloading in the cold

When all is said and done, volume is a more consistent measure for powder. Older powder will dry out and give higher velocities than fresh powder with equal weight but will remain the same with equal volume. This could explain a lot of so called variances between powder batches. I found this out the hard way years ago when I minored out in a IPSC match. I had just opened a new can of powder and when checking my powder measure with a scale I found the new powder was throwing heavy so I dialed down the measure..... and my velocity.

 

[High Binder]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"> volume is a more consistent measure for powder. </div></div>

I couldn't disagree more. Dry reagents are always measured by weight, that's chemistry 101 stuff. But even if that were not the case, the amount of water absorbed into a powder would have to be huge to affect the volume measurements you're touting, I bet what you were seeing was a difference in burn rate perhaps do to absorbed H2O, not a change in volume.

 

[1979brj]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: High Binder</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Take a coin that weighs more than your charge weight, and start cutting/filing it down until it weighs EXACTLY what your charge weight does.
</div></div>

Awesome idea!</div></div>

+. Great idea

 

[vinconco]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: High Binder</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"> volume is a more consistent measure for powder. </div></div>

I couldn't disagree more. Dry reagents are always measured by weight, that's chemistry 101 stuff. But even if that were not the case, the amount of water absorbed into a powder would have to be huge to affect the volume measurements you're touting, I bet what you were seeing was a difference in burn rate perhaps do to absorbed H2O, not a change in volume. </div></div>

The fact is the new batch of powder weighed more given the same volume than the older powder that I worked the load up with which had nothing to do with H2O (being a brand new can). Powder has residual reagents from the manufacturing process that will evaporate over time affecting the weight/volume ratio. Additionally, some powder measure manufactures use volume (cc’s) for their measures so I’m not sure about your assertion that “all” dry reagents use a weight measure.

 

[flyrodder]

Re: reloading in the cold

If you are going to use test weights (and you should), custom or otherwise, take a hint from the calibration and high-end lab folks and handle them with tweezers or forceps only so you don't add oils from your skin, which not only affect weight and corrosion potential but also attract dirt, compounding the effect.

 

[gitrdone44]

Re: reloading in the cold

Years ago we were hunting prairie dogs he loaded his 17 rem max when it was 35 degrees 6 months later its 103 he was popping primers, the only thing he could think what caused it was loading when it was cold. I do not know what load he used.

 

[High Binder]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: High Binder</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"> volume is a more consistent measure for powder. </div></div>

I couldn't disagree more. Dry reagents are always measured by weight, that's chemistry 101 stuff. But even if that were not the case, the amount of water absorbed into a powder would have to be huge to affect the volume measurements you're touting, I bet what you were seeing was a difference in burn rate perhaps do to absorbed H2O, not a change in volume. </div></div>

The fact is the new batch of powder weighed more given the same volume than the older powder that I worked the load up with which had nothing to do with H2O (being a brand new can). Powder has residual reagents from the manufacturing process that will evaporate over time affecting the weight/volume ratio. Additionally, some powder measure manufactures use volume (cc’s) for their measures so I’m not sure about your assertion that “all” dry reagents use a weight measure. </div></div>

You're totally neglecting to take into account other factors such as deviations in your scale etc...

What are these "residual reagents that will evaporate" and if these reagents 'evaporate' do you really think the 'evaporated' reagents would be significant enough to effect a volume change measurable to even the most advanced re-loader?

They use volume because it's faster and close enough for most applications.

 

[vinconco]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: High Binder</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: High Binder</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: vinconco</div><div class="ubbcode-body"> volume is a more consistent measure for powder. </div></div>

I couldn't disagree more. Dry reagents are always measured by weight, that's chemistry 101 stuff. But even if that were not the case, the amount of water absorbed into a powder would have to be huge to affect the volume measurements you're touting, I bet what you were seeing was a difference in burn rate perhaps do to absorbed H2O, not a change in volume. </div></div>

The fact is the new batch of powder weighed more given the same volume than the older powder that I worked the load up with which had nothing to do with H2O (being a brand new can). Powder has residual reagents from the manufacturing process that will evaporate over time affecting the weight/volume ratio. Additionally, some powder measure manufactures use volume (cc’s) for their measures so I’m not sure about your assertion that “all” dry reagents use a weight measure. </div></div>
What are these "residual reagents that will evaporate" and if these reagents 'evaporate' do you really think the 'evaporated' reagents would be significant enough to effect a volume change measurable to even the most advanced re-loader?

</div></div>

The point is that it didn't affect a volume change but a weight change. Bottom line is that powder will dry out change the volume weight. Powder is also hygroscopic so it can absorb moisture which will affect the weight/volume ratio.

 

[Beef82]

Re: reloading in the cold

Loading temperature doesn't matter, load testing temperature does, all powders are to some degree temp sensitive, that max or over max load that showed no pressure signs below freezing may do bad things when taken out in the high heat. For all temp sensitivity of powder is talked about, doubtlessly it effects accuracy, I've only heard of pressure issues, when temperature is all that changed, when the temp's in excess of 100 degrees.

 

[turbo54]

Re: reloading in the cold

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Beef</div><div class="ubbcode-body">...all powders are to some degree temp sensitive, that max or over max load that showed no pressure signs below freezing may do bad things when taken out in the high heat. For all temp sensitivity of powder is talked about, doubtlessly it effects accuracy, I've only heard of pressure issues, when temperature is all that changed, when the temp's in excess of 100 degrees. </div></div>


Very true. This summer, when doing 175smk development for my 308, I validated my "load" by setting them out in the sun on a 98º day to cook for an hour. They were too hot to keep in my fingers for more than a couple seconds at a time. This represents WORST CASE SCENARIO for me (not necessarily our boys in the sandbox).

Interestingly, I also ran them by my chrono this day, and found average velocity to be DOWN 15-20fps from a 75-80º day where they weren't allowed to cook in the sun, but they showed more pressure (very slight ejector marks). Powder was Varget, and we're talking 20 round groups for each test. SD was in the 6-8fps zone for "cool" cartridges, and SD was in the 15fps zone for the "hot" cartridges.