I always measure by weight because that’s how the load data shows it and that’s how powder is sold. But I noticed a shift in volume the other day on my progressive press that uses a powder drop (a volume measurement).
I also help my sister load own ammo, so she usually buys the same components that I buy, in this case, CFE Pistol powder. I cranked out a few hundred rounds of 9mm for myself and called it a day. The next day, I was getting things set up for her and when checking the powder weight on the scale, it was a heavier weight for that same volume. I had to adjust the powder drop to a smaller volume for her powder. Switching back and forth between her powder and mine, it’s consistently about a half turn difference on the powder adjust screw to get 5.2gns on the scale. Is this common?
Previously, we were going through multiple 1lb & 4lb jugs of Alliant Power Pistol and I never had to adjust the powder drop volume. It was always spot on the next time I started loading, regardless of which jug of powder I grabbed. It was very consistent from batch to batch.
It made me think back to old videos I saw of guys, “I’ve been loading for 40 years…” and they used a measuring scoop instead of weighing the powder.
On a side note, I’m not crazy about CFE Pistol. It burns really dirty. It made my stainless 1911 look like one of those scary black guns. 8lbs… that’s 10,769 rnds of soot I have to clean.
Any time you switch powders you have to re calibrate as they all have different densities. Some are heavier/lighter per volume due to the specific gravity of the powder. You will also find variations in weight between lots but it is usually inconsequential unless you are in high performance rifle rounds.
When I load for rifle, shotgun, or .44M, I use my RCBS Chargemaster, that has an automated trickler to dispense right onto the scale. It makes things a lot easier when I’m doing things on a single stage press. So I never noticed anything because the powder was always automatically weighed out for me.
In 2019, I bought a Dillon progressive press with the powder drop for 9mm & .45acp because I shoot a lot more of that. I’ve gone through a LOT of lbs of Win231 for .45 & Alliant PP for 9mm. Especially when ammo started drying up, I bought a lot of 1lb containers of powder from multiple stores driving all over as well as 4lb & 8lb online. I never noticed any variation from jug to jug. Then I switched to CFEPistol for 9mm because that’s all I could find.
What really struck me was that the difference in weight between one jug and the other was the difference from minimum charge weight and the maximum for that load. Although the weight itself wasn’t too much (less than 1gn), it was significant for that cartridge.
So how much weight does half a turn equal? Strange that you would significant variance between different containers of the same powder. Could one bottle been roughly handled causing the spheres to break into smaller pieces resulting in higher density per drop? I personally have not experienced this, but only thing I can think of besides a change in the way the powder is made.
I use Win 231 or HP-38 for my 9mm rounds. I buy whatever is cheapest or on sale at the time, so I end up with both powders in various jug sizes. Have not had to change the setting on my Dillon 550 dropper when one jug or brand runs out and I start on the next one. I always weight the drops when I start and randomly while I am loading.
Even when you are using the same powder you should reset everything when you switch from one lot to another.
Making powder is artwork and even the manufacturers will tell you to count on things being basically the same as long as your working with jugs of the same lot. Switch lots and you start from scratch.
That depends on the powder and apparently the lot#. The difference between two lots of CFE Pistol, it was about 0.7gn, which is the difference between the minimum and maximum weight for that load.
I always calibrate my scale and check several powder drops before I start loading a new batch. Because of the significant difference, I thought my previous 200rnds might be a little hot. I thought I did something wrong. So with the new batch, I double checked the weight about every 50rnds and it stayed dead on. Then I switched back to the first jug, readjusted the powder drop, and it stayed dead on for 400rnds.
I always calibrate my scale and then check the weight of the powder drop three times before I start loading a new batch. That’s how I caught the difference. I’ve just never had to make any adjustments to the powder measures before, after initially setting things up in 2019.
Good to know lot variation is common. Even though the weight of the powder is my primary focus, I still kept checking on my sister when we took the new batches to the range. “Is the recoil about normal? All the bullets are coming out of the barrel? Are they hitting the target about where you expect?” I guess I should actually make use of my chronograph. It’s been packed away for a while.