Rainy Day Vs Clear Day Powder Trows

under_dawg · March 15, 2009, 02:45 PM

I have a Lee Classic Turret with Pro-disk powder measure. I noticed yesterday it was throwing 6.5gr of powder very consistantly. Today the powder is weighing 6.4 grains very consistantly. I beleive it is throwing the same volume of powder, but different humidity amounts are causing weight variations. I'm just not sure if it could make a 1\10th of a grain difference. I decided to adjust my scales after the first several throws rather than adjust the powder flow because I feel certain the powder volume is the same. These are not target loads, just plinking and are in the middle of the start and max loads (plenty of room for .3 or .4 variations in powder). If this was a target load or very close to the min. or max. load, should you go with weight or volume? I was just curious if anyone else has noticed this.

Sevens · March 15, 2009, 05:25 PM

Can't ever go with volume when working with smokeless powder. It's always going to be weight. When you have a device that throws powder from a non-adjustable chamber, you get whatever it throws, not whatever the chart says that came with the device. Whether that's Lee's Pro Auto Disk or Lee's dippers.

It could also be your scale... especially if you keep "adjusting" the scale to match the load you assume your device is throwing.

If you are throwing a 6.5 grain charge, then 0.1 grain won't make as much difference as it would in say, a 2.8 grain charge. And in a larger cartridge case, it also won't make as much difference.

Also, I'd bet a lot of factory ammo varies by as much as 0.1 grain from round to round.

I agree with you when you say it's safe and you shouldn't be bothered a lot by it, but I don't agree with adjusting your scale to match the load you think your device is throwing.

Zero your scale, check it occasionally with a check weight or something of a known weight (I like to keep a FMJ .224 bullet handy, I know it weighs 55.1gr all the time) and don't adjust your scale to match the weight that you believe your device is throwing.

under_dawg · March 15, 2009, 05:54 PM

Thanks for the info. I didn't mean I adjusted the scale's zero, I meant I just changed the indicator to 6.4 instead of 6.5 to match what the the powder measurer is throwing. The volume it's throwing is the same (I hope) because the cavities haven't changed. I was just curious what effects humidity has on weight. It would be interesting to get a barometer and record the readings using the same cavities with different temps and humidity.

Oberg · March 15, 2009, 06:09 PM

The earths gravity changes throughout the day. Did you reload them in morning and evening? Or even times of the month are different. I don't know it if would change it but that plus air pressure humitity and all that jazz could end up effecting it. just my pennies in the pot. I've never noticed that.

March 15, 2009, 02:45 PM	#1
under_dawg Senior Member Join Date: November 15, 2007 Location: Cayce, SC Posts: 222	Rainy Day Vs Clear Day Powder Trows I have a Lee Classic Turret with Pro-disk powder measure. I noticed yesterday it was throwing 6.5gr of powder very consistantly. Today the powder is weighing 6.4 grains very consistantly. I beleive it is throwing the same volume of powder, but different humidity amounts are causing weight variations. I'm just not sure if it could make a 1\10th of a grain difference. I decided to adjust my scales after the first several throws rather than adjust the powder flow because I feel certain the powder volume is the same. These are not target loads, just plinking and are in the middle of the start and max loads (plenty of room for .3 or .4 variations in powder). If this was a target load or very close to the min. or max. load, should you go with weight or volume? I was just curious if anyone else has noticed this.

March 15, 2009, 05:25 PM	#2
Sevens Senior Member Join Date: July 28, 2007 Location: Ohio Posts: 11,756	Can't ever go with volume when working with smokeless powder. It's always going to be weight. When you have a device that throws powder from a non-adjustable chamber, you get whatever it throws, not whatever the chart says that came with the device. Whether that's Lee's Pro Auto Disk or Lee's dippers. It could also be your scale... especially if you keep "adjusting" the scale to match the load you assume your device is throwing. If you are throwing a 6.5 grain charge, then 0.1 grain won't make as much difference as it would in say, a 2.8 grain charge. And in a larger cartridge case, it also won't make as much difference. Also, I'd bet a lot of factory ammo varies by as much as 0.1 grain from round to round. I agree with you when you say it's safe and you shouldn't be bothered a lot by it, but I don't agree with adjusting your scale to match the load you think your device is throwing. Zero your scale, check it occasionally with a check weight or something of a known weight (I like to keep a FMJ .224 bullet handy, I know it weighs 55.1gr all the time) and don't adjust your scale to match the weight that you believe your device is throwing. __________________ *Attention Brass rats and other reloaders:* I really need .327 Federal Magnum brass, no lot size too small. Tell me what caliber you need and I'll see what I have to swap. PM me and we'll discuss.

March 15, 2009, 05:54 PM	#3
under_dawg Senior Member Join Date: November 15, 2007 Location: Cayce, SC Posts: 222	Thanks for the info. I didn't mean I adjusted the scale's zero, I meant I just changed the indicator to 6.4 instead of 6.5 to match what the the powder measurer is throwing. The volume it's throwing is the same (I hope) because the cavities haven't changed. I was just curious what effects humidity has on weight. It would be interesting to get a barometer and record the readings using the same cavities with different temps and humidity.

March 15, 2009, 06:09 PM	#4
Oberg Senior Member Join Date: April 7, 2008 Location: Minn Posts: 212	The earths gravity changes throughout the day. Did you reload them in morning and evening? Or even times of the month are different. I don't know it if would change it but that plus air pressure humitity and all that jazz could end up effecting it. just my pennies in the pot. I've never noticed that.