Charge Weight Changed Overnight

[alamogunr]

I was loading some .45 ACP with 7 gr of Accurate #5, a minimum load. I got interrupted and left everything in place. When I got back to finish, I checked the measure setting on the scale and it indicated that the measure was now throwing about 7.7 gr. What would cause that much difference? Does ball powder settle to the point that the volume would change the weight thrown by the measure?

I always check the measure setting on the scale when I start, about every 40-50 charges, and when I finish. I've never had this happen with other powders, but I've never left the powder in the hopper overnight before either.

[Arlin]

John:

I have experienced this same thing before with Accurate powders. I believe you may have hit the nail on the head with the settleing. My reloading room is on the second floor of my garage and there is noticable vibration from the highway. I believe the vibration may cause the settleing. Did you happen to check the powder weight on the first case or did you run a few through first? On my Dillon 650 I let a few cases go through before I check the load. If everything is ok I then start setting the bullets.
Arlin

[alamogunr]

John:

I have experienced this same thing before with Accurate powders. I believe you may have hit the nail on the head with the settleing. My reloading room is on the second floor of my garage and there is noticable vibration from the highway. I believe the vibration may cause the settleing. Did you happen to check the powder weight on the first case or did you run a few through first? On my Dillon 650 I let a few cases go through before I check the load. If everything is ok I then start setting the bullets.
Arlin

I checked the weight on the first case. I immediately backed off to about 7.3 grains. I had intended to load about 50 rounds with a slightly heavier charge anyway. I probably should have checked the last case but didn't, so I don't know if it changed between the first and last case charged after the delay.

[leadman]

If the cap was off the measure the powder could have absorbed some moisture. Don't have that problem here in Phoenix much.
Did you try replacing the powder in the measure with powder from the container to see if it weighted the same?

[762 shooter]

Alamognr,

I have had settling in the measure just from vibration of working on my bench for ten minutes in between.

After you throw a couple of charges did the charge get right or did it stay high?

That first charge on mine can be high/settled but after 2 or 3 throws they are OK again.


762

[alamogunr]

The cap on the powder hopper was never removed. My loading room is in my shop which is heated/air conditioned, although in the weather we have been having, the humidity could have crept up.

After adjusting the measure to 7.3 gr. I checked it the same way as always, only this time I only loaded 50 more rounds so the check was at the beginning and the end of the last session. No difference.

The powder was not removed from the hopper either. I may change my routine to include pouring the powder back in the container if I interrupt my loading for more than a couple of hours.

[9.3X62AL]

I long ago got in the habit of running 5-6 charges through the measure after taking ANY significant pause in the reloading effort, them checking the weight to confirm that things haven't gotten creative.

[canyon-ghost]

Temperature changes in the room effect your scale too. If the room gets hotter or cooler, the scale setting will change. That's just another factor.

Ron

[largom]

This is why I weigh all charges.

Larry

[uscra112]

Temperature changes in the room effect your scale too. If the room gets hotter or cooler, the scale setting will change. That's just another factor.

Ron

+1 to that it it's an electronic scale. Those things are awfully temperamental.

Kinda doubt that temperature would affect a balance though. . . . .

[762 shooter]

Alamognr,

Electronic or balance?

762

[redneckdan]

Temp will affect a balance scale. Whether you notice it or not depends on the resolution of your instrumentation.

[alamogunr]

My scale is a balance type(RCBS 505). The temperature in my shop doesn't vary much. I've never noticed it affecting the scale. I don't have a set of test weights but I do use various jacketed bullets to check the scale to make sure it isn't grossly inaccurate.

[morgans]

Hello all, I work on alot of time related items, I record Temp ,humitdy and so on everytime I work on things, anyways if you run a few experiments and record your data you will find slight changes in just about anything., This is just coming from me working with alot of different metals, thought it might help some,when I get into reloading I will run thru what you guys are talking about and see what I come up with, sounds like a cool project

[wv109323]

You did not mention the brand of powder measure but the the baffle plate ( or lack thereof)makes a difference. I always pour my powder in so that it is 2-3 inches above my baffle plate of my RCBS Uni-Flow. I then tap on the measure's tube 15-20 times to settle the powder before I start to weigh any charges.
I try to measure all charges at one setting and then return the unused powder into a sealed container. Powder will asorb moisture and electronic scales will vary according to room temperture. I have my electronic scales near a furnace wall register and notice a variation if the A/C kicks on.