Checking powder lot consistency by volume with a scale

[insight3b]

I just wanted to pass on a trick I learned on how to check any powder's consistency when changing from one lot to another lot of the same powder WITHOUT shooting the load.
You'll need a hand thrown powder measure(like a Uni-flow) 2 different lots of the same powder and a scale.
Set up your powder measure to throw a desired charge of the first lot by weight(I throw a tenth or two low and trickle up)
After you are throwing the same charge consistently...empty the barrel in the powder measure and refill with the 2nd lot of powder...DO NOT adjust the powder measure.
Throw a charge of the new/2nd lot and weigh(can use either balance beam or electronic scale) and wait to be amazed.
The ONE consistent result of weighing ALL powders is that the scale will not read near the same weight as the previous lot.
Pretty cool to see the difference when using a beam scale.
Again you are checking the powder by volume by using a scale and it is the ONLY way to check powder lots without shooting the load. Another reason a hand thrown powder measure is worth its weight in gold.
Hope this makes sense and helps

 

[paul2atlo8]

What if the chemical process was changed in creating the powder(more or less nitrocellulose, graphite, retardants,ect). however the volume by weight stayed close. Wouldn't the only way to find
the true difference would be to shoot the new lot then compare it to the other? Or use a pressure strain gauge attached to the barrel? I think that would determine the true pressure curve for the new lot of powder?
Black powder you can compare that way, smokeless different story just my .02.

 

[insight3b]

The only way to know the difference is to shoot. Two different lots of the same powder should take up close to the same volume. You set the screw to open/close the chamber in your powder measure to throw a charge(volume) and weigh it...empty the powder measure and without touching the adjustment screw fill with the new lot and throw a charge. Now you have the same amount of volume as the previous lot so technically it should weigh the same. It rarely comes close but how much difference in weight between the two will tell whether you need to drop back to start charge or simply tweak the load

 

[Pinecone]

No, it does not tell you if and how the powder is different when firing.