leadmonkey
01-23-2014, 08:24 PM
I use the Lee Standard Auto Disk powder measure with the adjustable charge bar for all my reloading. It works very well on charges over about 5 grains, but I never have been able to get it to consistently meter smaller quantities, especially flake powders like Unique. What happens is that when the charge bar is adjusted down to its smallest limit, the transfer area is unevenly proportioned. It is tall and thin, creating more opportunity for variation in the volume of powder that falls into it. At say, 3 grains I get 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 Micro Disk compensates for this inability to meter small charges by reducing the height of the transfer space, making the volume for the flakes to fill more even in all dimensions. It works, but I never did like the idea of having to remove the powder measure, dump the powder, disassemble the measure, change the disk setting, reassemble the measure, reinstall the measure, just to change the charge weight.
What I did was reduce the thickness of the charge bar, making the transfer area in it a more evenly proportioned volume at the small settings, just like the Micro Disk does. An additional benefit is that it is fully adjustable. No disassembly is required to change the charge volume. This works great for small charges with usually difficult flake powders.
Note that modifying this measure as below renders it useless on any charge over about 6 grains. Changing it back so it will work for all the normal sized charges can be done if you have a spare hopper, charge bar, and charge lever, but it involves swapping these parts out. It's a lot of trouble. You might want to have an extra powder measure for all your larger charge sizes.
First, disassemble the charge bar and fill all the voids in it except the slot for the charge lever 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.
94381
Once the epoxy has set up well, sand the top of the charge bar down from approximately .450 inch thickness to .300 inch. I used a belt sander. 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, and you don't want to sand too far. 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.
You'll have to Fabricate a new thread adjuster. I drilled in the end, and used a 4-40 screw and some nuts, more or less in the same manner that the original screw adjuster was.
94382
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 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 clearances right, the charge bar will bind, or it will leak, or both. Don't ask me how I know this.
You'll have to drill the screw holes a bit deeper too.
94383
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. It took some doing, but it works nicely, and was worth the trouble.
94384
There are a couple of minor modifications you can make to the body of the measure itself to assure that the charge bar traverses the exact distance needed for a full transfer. As soon as I dig up the pictures, I'll post them.
The Micro Disk compensates for this inability to meter small charges by reducing the height of the transfer space, making the volume for the flakes to fill more even in all dimensions. It works, but I never did like the idea of having to remove the powder measure, dump the powder, disassemble the measure, change the disk setting, reassemble the measure, reinstall the measure, just to change the charge weight.
What I did was reduce the thickness of the charge bar, making the transfer area in it a more evenly proportioned volume at the small settings, just like the Micro Disk does. An additional benefit is that it is fully adjustable. No disassembly is required to change the charge volume. This works great for small charges with usually difficult flake powders.
Note that modifying this measure as below renders it useless on any charge over about 6 grains. Changing it back so it will work for all the normal sized charges can be done if you have a spare hopper, charge bar, and charge lever, but it involves swapping these parts out. It's a lot of trouble. You might want to have an extra powder measure for all your larger charge sizes.
First, disassemble the charge bar and fill all the voids in it except the slot for the charge lever 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.
94381
Once the epoxy has set up well, sand the top of the charge bar down from approximately .450 inch thickness to .300 inch. I used a belt sander. 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, and you don't want to sand too far. 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.
You'll have to Fabricate a new thread adjuster. I drilled in the end, and used a 4-40 screw and some nuts, more or less in the same manner that the original screw adjuster was.
94382
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 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 clearances right, the charge bar will bind, or it will leak, or both. Don't ask me how I know this.
You'll have to drill the screw holes a bit deeper too.
94383
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. It took some doing, but it works nicely, and was worth the trouble.
94384
There are a couple of minor modifications you can make to the body of the measure itself to assure that the charge bar traverses the exact distance needed for a full transfer. As soon as I dig up the pictures, I'll post them.