Lee Auto Disk Powder Measure Graph

[Fourbits]

Here’s an Excel graph that will let you estimate the right Lee Auto Disk cavity size for four powders. The powders are: 2400, W231, Bullseye, and Unique. I use these powders for pistol loads from 9mm to 44 Magnum. I guess you need to know that the values for the cavities in the disks are actually volumes in cubic centimeters (cc).

Hope this is useful.

 

[The Bushmaster]

Not sure why I would need that as I have the values chart that came with my Lee Auto Disk and have blown it up to twice the size...Anyone?

 

[mccook8]

Maybe your chart is more accurate than mine, Bushmaster.

I had to go up two sizes to get it to throw the weight I wanted (6.0gr) of Unique.

 

[BsChoy]

In any event, thank you fourbits

 

[Fourbits]

The reason I did this is I also found that the Lee tables were way off.

Fourbits

 

[The Bushmaster]

The Lee tables are accurate on those days that the humidity is just right. Even volume varies because of the humidity and how much the powder is compressed in the cavity. I will go by weight as much as possible. Most people on here know that I am annel about my powder charges and weight every charge that I put in a case whether it's handgun or rifle because of the variances created by humidity and powder density...

Fourbits...I am using the charts that came with my Lee Auto disk that I purchased 20 years ago and the most I have found them to be off is by +/- .2 to .4 grains at any given time and humidity plays a large part with this "inaccuracy". Most of the time they tend to be right on +/- .1 grain.

 

[LotI]

And just in case anyone has lost theirs, it's attached. Or you can get it here

 

[Fourbits]

This may turn into something interesting! I live in a very dry climate. Maybe thats the issue. If powder weights change with humidity we are measuring water! Has anybody seen a chart giving powder weight versus humidity?

 

[Fourbits]

Should we start a new thread on powder weight versus humidity?

 

[schloe]

Bushmaster - He didn't say you needed this, but maybe somebody else does?

 

[Fourbits]

Well I guess I had to do it. Here's a graph of My data versus the Lee data. It confirms that I see quite a difference.

I sure don't want to say my data is better. It's what I got after years of reloading with Unique. As I said at the start of this the graphs can be used to ESTIMATE the disk volume you need.

Thanks for all the input!

 

[ForneyRider]

My W231 and Power Pistol have been right on in Lee Auto Disk.

The H110 is very messy, but works too.

 

[gandog56]

The Lee tables are accurate on those days that the humidity is just right. Even volume varies because of the humidity and how much the powder is compressed in the cavity.

Then the humidity is NEVER right at my house. I always find the tables from Lee weigh light. I did some Excel spread sheets for various powders made by averaging ten throws from every cavity. They all weigh less than the tables.

 

[snuffy]

In order for humidity to affect how much powder weighs, powder has to absorb it. I don't believe that smokeless powder absorbs humidity/water. It's just not hygroscopic.

Tests have been done time and again on ammo loaded in high humidity and low humidity, no difference. I don't like to load when it's hot and humid, I'd rather be out shooting. That's why I'm doing most of my loading right now!

 

[Fourbits]

Snuffy,

That makes sense. I think the Lee tables are just conservative for safety.

 

[The Bushmaster]

Snuffy. I'm not so sure that it doesn't effect the scale rather then the powder. As I weigh every powder charge that I drop in a case. I have noticed that depending on the day (rainy or sunshinny) that the powder charge varies about +/- .2 grains on any given day. I adjust for it using a trickler...To me it really isn't a problem, but to others, it seems to be...And yes...The Lee tables are a bit conservative...Lawyers and all you know...

 

[gandog56]

I find them WAY conservative.

 

[freakshow10mm]

The standard rule of thumb is move up two disks from what the chart says and that should be it.

 

[ForneyRider]

I highly recommend checking them with a scale.
The Lee 20$ scale is hard to beat.
Dillon, RCBS, Hornady, Lyman all make good ones too, just cost 2-4 times as much as the Lee.