Jager
Gold $$ Contributor
A couple weeks ago XTR posed an excellent question… does leaving powder overnight in a powder measure or auto trickler affect its consistency? (https://forum.accurateshooter.com/threads/leaving-powder-out-in-throw.4032824/#post-38044705)
And then, a few days later, Bolt Action Reloading posted this rather breathless bit of news over on his YouTube channel:
Now I confess to never having worried much about such details in the past. I have left various powders overnight in a powder measure or auto trickler many times, without any affect that I could observe. But I’m always open to learning more about this ever intriguing craft of ours. And so I did three things.
First, I added a new column to my electronic handload log called “Relative Humidity – Powder Exposure.” That was so I could begin tracking the humidity level my powder was exposed to during the time that load was being created… the period during which the powder was out of its factory canister.
Second, I instituted a new rule. “Self,” I told myself, “you are no longer allowed to let powder sit out in a measure or trickler any longer than necessary.” No more “I’ll finish this batch after supper,” or “I’m shooting this ladder tomorrow so I’ll just leave everything set up in case I want to extend the charge range or repeat any of the loads.” The goal was to get any unused powder back into its factory container as quickly as possible.
And third, I selected three cans of powder from the shelf… an old, half-used, 30 or 40-year-old can (the old metal canister) of W296; a new, few-months-old (plastic canister) bottle of W296; and a new, fresh (plastic canister) bottle of IMR-4227.
Of note, the old batch of W296 was perfectly fine. I had crafted several loads of .300 Blackout with it a few months ago and it performed exactly as expected.
I carefully measured out 20.0 grains of each powder using my A&D FX-120i balance, then poured each of those three charges into an evaporating dish. The three dishes were placed on a shelf. The temperature was 68F and the relative humidity was 56%.
Now my loading bench is in the corner of a bedroom. Which is to say, componets are not exposed to the humidity of a basement or the heat of an attic or garage. On the other hand, my house is nearly a hundred years old and that bedroom has no heat other than that which makes its way upstairs from the wood stove. Cooling during the warmer months comes from a window AC unit. All of which is to say, I probably see more temperature and humidity variance than you boys and girls with more modern homes that have central heating and cooling.
For my three powder samples, I waited sixteen days. During that time the samples saw temperatures from 63 to 77 degrees; and relative humidity from 24 to 53%. Environmentals were captured with a Kestrel Drop data logger, at ten-minute intervals.
I honestly expected to see something. Some variance. But when I finally sat down yesterday afternoon – with the temperature at 70F and the relative humidity at 49% - to re-measure those charges… they came out at 20.0 grains for both the old and the new W296 samples; and 19.98 grains for the IMR-4227 sample. And since that IMR-4227 measurement was within a single measuring tick (the A&D FX-120i has an accuracy spec of 0.02 gr.) I consider that noise.
The samples were unchanged.
That’s not necessarily the whole story, of course. It might be that smokeless powder loses moisture – and, hence, weight – at low humidity levels; and then re-absorbs moisture as humidity climbs. Testing at humidity extremes ought to show that, if it’s the case.
And a much more comprehensive test using a known good load, created under different environmental conditions, and then observing actual field results, might be interesting.
But I think, mostly, I’m not going to worry about it.
And then, a few days later, Bolt Action Reloading posted this rather breathless bit of news over on his YouTube channel:
Now I confess to never having worried much about such details in the past. I have left various powders overnight in a powder measure or auto trickler many times, without any affect that I could observe. But I’m always open to learning more about this ever intriguing craft of ours. And so I did three things.
First, I added a new column to my electronic handload log called “Relative Humidity – Powder Exposure.” That was so I could begin tracking the humidity level my powder was exposed to during the time that load was being created… the period during which the powder was out of its factory canister.
Second, I instituted a new rule. “Self,” I told myself, “you are no longer allowed to let powder sit out in a measure or trickler any longer than necessary.” No more “I’ll finish this batch after supper,” or “I’m shooting this ladder tomorrow so I’ll just leave everything set up in case I want to extend the charge range or repeat any of the loads.” The goal was to get any unused powder back into its factory container as quickly as possible.
And third, I selected three cans of powder from the shelf… an old, half-used, 30 or 40-year-old can (the old metal canister) of W296; a new, few-months-old (plastic canister) bottle of W296; and a new, fresh (plastic canister) bottle of IMR-4227.
Of note, the old batch of W296 was perfectly fine. I had crafted several loads of .300 Blackout with it a few months ago and it performed exactly as expected.
I carefully measured out 20.0 grains of each powder using my A&D FX-120i balance, then poured each of those three charges into an evaporating dish. The three dishes were placed on a shelf. The temperature was 68F and the relative humidity was 56%.
Now my loading bench is in the corner of a bedroom. Which is to say, componets are not exposed to the humidity of a basement or the heat of an attic or garage. On the other hand, my house is nearly a hundred years old and that bedroom has no heat other than that which makes its way upstairs from the wood stove. Cooling during the warmer months comes from a window AC unit. All of which is to say, I probably see more temperature and humidity variance than you boys and girls with more modern homes that have central heating and cooling.
For my three powder samples, I waited sixteen days. During that time the samples saw temperatures from 63 to 77 degrees; and relative humidity from 24 to 53%. Environmentals were captured with a Kestrel Drop data logger, at ten-minute intervals.
I honestly expected to see something. Some variance. But when I finally sat down yesterday afternoon – with the temperature at 70F and the relative humidity at 49% - to re-measure those charges… they came out at 20.0 grains for both the old and the new W296 samples; and 19.98 grains for the IMR-4227 sample. And since that IMR-4227 measurement was within a single measuring tick (the A&D FX-120i has an accuracy spec of 0.02 gr.) I consider that noise.
The samples were unchanged.
That’s not necessarily the whole story, of course. It might be that smokeless powder loses moisture – and, hence, weight – at low humidity levels; and then re-absorbs moisture as humidity climbs. Testing at humidity extremes ought to show that, if it’s the case.
And a much more comprehensive test using a known good load, created under different environmental conditions, and then observing actual field results, might be interesting.
But I think, mostly, I’m not going to worry about it.
