Lee Auto Disk/Charge Bar Modification

[leadchucker]

I only reload pistol ammo, and I use the Lee Standard Auto Disk powder measure with the adjustable charge bar for all my reloading. The setup works very well for powders like W231 and Universal, but I never have been able to get it to consistently meter Unique in small quantities.

When the charge bar is adjusted down to its smallest limit, it presents a tall thin charge transfer space for the powder to fill. The large flakes do not fit well in this space, and I got variations of up to two tenths of a grain. That's not good when the start charge is 2.9 gr, and the max charge is 3.2 gr.

The charge transfer space in the Micro Disk is half the height of the standard disks or the charge bar, making the volume for the flakes to fill more even in all dimensions.

You can reduce the thickness of the charge bar, and it will perform much like the micro disk. An additional benefit is that it is fully adjustable. No disassembly is required to change the charge volume. It takes some doing, but it works nicely, and was worth the trouble. This works great for small charges with usually difficult flake powders, but it now won't do charges much over about 6 or 7 grains. You'll still have to have another powder measure for larger loads.

First, disassemble the charge bar and fill all the voids in it with epoxy.
Note that the original screw adjuster must be cut apart to disassemble the unit. It's far too thick and can't be used anyway.


Once the epoxy has set up well, sand the top of the charge bar down from approximately .450 inch thickness to .250 inch. I used a belt sander. It takes some care and constant checking with a caliper to get the surface even and consistent. For the final sanding, use a sheet of sandpaper on a nice flat surface, and take very small amounts off at a time, constantly checking your thickness at each end and each edge.
Fabricate a new thread adjuster. I used a 4-40 screw and some nuts.


Grind the edges of the hopper down the same amount that the charge bar was ground down. This will restore the zero clearance between the mating surface of the hopper and the top surface of the charge bar.
This also takes some particular care and accuracy to get the clearance just right. Go slow, and be sure to remove the same amount of material from each side and corner. You'll have to drill the screw holes a bit deeper too.


Here is the unit completely assembled. You'll also have to grind some metal off of the top of the charging lever to give clearance for this thinner charge bar.
This setup will charge 380 ACP cartridges with 3 grains of Unique with less than a tenth grain variation.

 

[sexybeast]

Good write up. I tried using the adjustable charge bar a few times doing .32 auto and even with hp38 they still were too far off. I set it for 2.5gr and dropped four charges and together they only weighed 8.6gr when they should have been 10.0 gr.
I'm going to load some 38 special soon with a load of 3.0gr of titegroup behind a 148 lead wadcutter. The smallest hole in the disc is .30 which drops 3.4gr of titegroup. I will try this as I have two adjustable charge bars and I don't mind experimenting with one. Maybe I can have some confidence in the thing!

 

[leefan]

For another calibre I get 3 grains of Titegroup with the 0.27 cc microdisk. I have several adjustable charge bars and they won't dispense Titegroup reliably below about 3.4 grains. And the cc/grain varies significantly over the adjustment range. But since the standard disks are fiendishly designed so that few of them dispense the commonly desired volumes of TG, the bars are a must for me. I have four of them adjusted for four calibres.

 

[sexybeast]

I've never heard of seen a .27cc microdisc for the lee powder disc measure? Is it something you made or something new?

 

[Schwing]

This is a great idea! I have been struggling to get consistent loads under 3 grains with several powders (Unique, Promo, Blue dot). I think I am going to order another charge bar and try this out. I have a spare hopper.

Thanks for sharing!

 

[leadchucker]

If you try it, make sure you sand each piece of the charge bar down evenly, and make sure both pieces are exactly the same thickness. You don't want one end or one side thicker than the other.

Same goes for the hopper. You want the contact area to sit perfectly flat on the charge bar, so those contact areas at the edge need to be perfectly even and straight. Getting this right is the toughest part.

If you don't get these things right, the charge bar will bind, or it will leak, or both. Don't ask me how I know this. :banghead:

Modifying this measure this way renders it useless on any charge over about 7 grains. Changing it back so it will work for all the normal sized charges involves swapping out the hopper, charge bar, and charge lever. It can be done, but it's a lot of trouble. You might want to have an extra powder measure for all your larger charge sizes.

 

[higgite]

I've never heard of seen a .27cc microdisc for the lee powder disc measure? Is it something you made or something new?

Lee discontinued them. The mold broke. This is what one looks like.

 

[Schwing]

I bought a third party version of this from a guy on ebay a couple of weeks ago. It looks like that only it looks to be made out of some kind of clear resin. I tested it out a couple of days ago and had the same issues that I have with the charge bar. It drops perfectly if you are using something like bullseye but when you try powders like Unique or promo, it drops +-.3 grains. Those flake powders seem to get worse and worse the smaller the charge you are trying to throw.

 

[sexybeast]

I have never seen one of those before. I've been using a powder disc measure for ten years now.
The problem with flake powders is the issue with measuring small amounts. I remember someone asking about using 700x for 9mm. The charge would have been around 3.5gr or so. I tried it once and just could not trust it to be close. I just can't use a powder that won't measure. You could replace 700x with unique, Red Dot, Promo [same thing], or even bullseye.
I'm use to titegroup and hp38. Night and day when compared to Red Dot!

 

[leadchucker]

The Micro Disk is indeed no longer available from Lee, but you can get the copy from the guy on evilbay. With shipping, it will cost over $27.

The Micro Disk does deliver pretty consistent small weight throws every time, even with flake or extruded powder, but you only have those six holes in the disk to choose from. One hole may not deliver quite enough, and the next larger hole will deliver too much.

Plus, it's a pain to remove the powder measure, dump the powder, disassemble it and change the disk setting, reassemble it, reinstall it, and add the powder again, just to change the powder throw weight.

 

[wackemanstackem]

There is also another fix for this problem and its very easy to do.If you take a deck of playing card cut off some small pieces to start ,then put them against the face slot of the charge bar right where it is v.Bend them and put 4 0r 5 in there with some glue and shave them off so they dont stick up and what this does is move the void forward over the drop hole in the bottom .It works really great and is very simple to do.I learned this from an expert on another forum who had problems going under 5 on the charge bar,since doing this I have been as low as 3 and its right on.

 

[Lost Sheep]

(edited for brevity)
Plus, it's a pain to remove the powder measure, dump the powder, disassemble it and change the disk setting, reassemble it, reinstall it, and add the powder again, just to change the powder throw weight.

Don't dump the powder. Turn the entire assembly upside-down (with the hopper lid on, of course).

 

[Potatohead]

The mold broke.

Couldn't they make a mod for it?

It would fit right in!




I like Lee. Just makin a joke.

 

[Potatohead]

Seriously though, nice work on the charge bar..a little to precise for me to handle though.