Lee ProAuto Disk mods

[preacherJohn]

I recently started reloading 40 S&W after acquiring two pistols in that caliper this year. One is my M&P performance center Shield that was on sale with a LARGE rebate to boot; and the other was just a casual stroll past the gun case impulse buy @ Cabellas when I noticed a Sig P226 on clearance marked down several hundred dollars! (wished I never went over there, I just couldn't resist it, LOL). Of course I had to order some dies and just got those set up this past week. After hand loading and hand measuring some test rounds, I found a few that worked pretty well, good accuracy, and not too hard on my wrist. What I did was use the Pro Auto Disk to throw a starting powder charge around 5.6-5.8gn's and then trickled the rest on my digital scale to the amount I wanted. 6gn's of WSF worked real well with the 165 Xtreme FP's. I've seen some post whereas people were modifying one hole on a disk to drop the amount they wanted. My question is has anyone done this with this amount of this powder, or something really similar? If so, what size drill bit did you use, or how much material did you remove from the hole you drilled? Be specific if you can and what number hole you used such as the .43 or .49cc etc. Thanks.

 

[kcofohio]

https://www.thehighroad.org/index.php?threads/working-diy-micro-auto-disk.741988/#post-9318360

#1 post, bds has some pictures and discussion.

 

[LiveLife]

I wanted 6 gn's of WSF ... what size drill bit did you use, or how much material did you remove from the hole you drilled? Be specific if you can and what number hole you used such as the .43 or .49cc etc.

Use .53 hole which will drop 6.3 gr of WSF and adjust down to 6.0 gr - https://leeprecision.com/cgi-data/instruct/AD2302.pdf

I went to the local Home Depot and bought a package of #10-32 x 1/2" brass machine screws with size of head that was smaller than the thickness of the Auto Disk. I used a drill bit slightly smaller than the screw and drilled about the center of the disk hole. After I screwed the brass screw in and out, the hole was nicely tapped with threads for "micro" adjustment. After cleaning up the hole burrs, I was ready for powder drop measurements.

 

[preacherJohn]

Ahh, this is EXTREMELY helpful and exactly what I was looking for. I have some 10-32 machine screws laying around, although not brass but zinc that would work just fine until I picked up some brass (don't really think it would make a difference except for "prettyness"). Seeing how it's Saturday, cold outside, and a good day for college football, I'll just venture down the basement and drill one of my disk out. You're right on about the .53cc disk dropping 6.3gr, I've already weighed them. Can't wait to try this out. GREAT TIP! Thanks man.

 

[LiveLife]

You are very welcome. Anything to help a fellow THR member and a man of God.

 

[Dudedog]

You can get a good idea of what a disk will drop by figuring the VMD of your powder some powders are close to listed VMD some are not.
WSF has a listed VMD of .084 but my jars are closer to .92 when I worked it out.
gr*VMD=cc and cc (disk size)/VMD=gr also disk size (cc)/gr = vmd
so for example .53 disk / 5.8gr = VMD of .0913
At WSFs listed VMD of .084 a .53 disk is about 6.4 gr, my lots which seem to have a higher VMD .092 (fluffier) a .53 disk with my lot would be closer to 5.8gr (caculated)

You want 6gr so with my VMD that would work out to a .55 disk which does not exist.
The .57 disk would be about 6.2 with my lot which is heavy

If you want to figure out what VMD you powder really is take a couple disk in the range you expect to use (smaller ones or large ones)
in this case for pistol I would take maybe a .43, a .53 and a .61. Throw and weigh the charges

I attached an Excell spreedsheet I set up to do the calcs (no marcros in the sheet)
It also has some load data. I believe I copied the load data into it correctly but Verify my numbers, I have been know to make typos.
If you put the VMD in cell K1 in the page labeled calcs it will calc what size disk you need for a charge.

Click on the .zip file and your PC should ask you to save it.

BDSs screw mod works well.
If you are not concerned with it being adjustable you can enlarge a smaller hole to the correct size with some sandpaper. If I have changed one I put a dab of nail polish around it so I know I have changed it. (had some orange polish on hand, a light colored paint would work just as well)

Side note- the Lee pro autodrum works well and is easy to adjust-good value for the money.

PS: You can use the Lee Pro disk on an LNL progressive if you get one. (need Lee powder drop die for the caliber)
About your PTX question in another thread Lee pistol powder drop dies have a "PTX" in them so the powder drop die expands the case mouth.

 

[Rule3]

Or for around $35 just buy the LEE AUTO DRUM powder measure and save all the fiddling around and measure out the exact powder charge you want.

I am all for saving a buck but after using the Prod Auto Disk, powder bar, double damn disks, etc the AUTO drum is far better.

 

[Dudedog]

Just remember if you go from the Pro Disk to the Autodrum when you go to dump powder the hopper on the Autodrum is not screwed on.
I forgot once at first.........
Like the Autodrum

 

[LiveLife]

Or for around $35 just buy the LEE AUTO DRUM powder measure and save all the fiddling around and measure out the exact powder charge you want.

I am all for saving a buck but after using the Prod Auto Disk, powder bar, double damn disks, etc the AUTO drum is far better.

Actually my C-H 502 micrometer powder measure on the Dillon 650 is better.

Just kidding.

While $35 Auto Drum is a viable option, for those who already have Pro Auto Disk and happy with it, this $1 mod allows infinitely adjustable powder metering option that can simply be achieved with a drill bit.

Beside, how many powder measures do you know that can meter W231/HP-38 down to 2.0 gr and Bullseye down to 1.5 gr with .1 gr variance? https://www.thehighroad.org/index.php?threads/working-diy-micro-auto-disk.741988/#post-9318360

25ACP, 32ACP and 380Auto reloaders rejoyce!

 

[Rule3]

Actually my C-H 502 micrometer powder measure on the Dillon 650 is better.

Just kidding.

While $35 Auto Drum is a viable option, for those who already have Pro Auto Disk and happy with it, this $1 mod allows infinitely adjustable powder metering option that can simply be achieved with a drill bit.

Beside, how many powder measures do you know that can meter W231/HP-38 down to 2.0 gr and Bullseye down to 1.5 gr with .1 gr variance? https://www.thehighroad.org/index.php?threads/working-diy-micro-auto-disk.741988/#post-9318360

25ACP, 32ACP and 380Auto reloaders rejoyce!

But once you add the screw to one of the metering holes you can not use the other holes on the disk without removing it.

I was happy with the Pro Auto Disk and still have my charts on what MINE threw for the powders I used. I was adaptable to whatever the predertimed amount was. I do not care too much about 0.1 gr variance.

 

[LiveLife]

Pro Auto Disk ... can meter W231/HP-38 down to 2.0 gr and Bullseye down to 1.5 gr with .1 gr variance

I do not care too much about 0.1 gr variance.

Really? I consider powder drop variance of less than .1 gr good enough for match loads and used Pro Auto Disk for my USPSA loads.

So how well does your current powder measure meter?

These are actual 10 drops weighed on 0.02 gr resolution Gemini-20 digital scale verified with Ohaus ASTM Class 6 check weights (Pro Auto Disk used is several years old and hopper was lightly tapped 10 times after filling with powder to settle powder and cycled 10 times with powder drops dumped back in the hopper):

NOTE: Since small powder granules go into the primer hole/pocket, care was exercised to tap out all the powder granules. Often reloaders will weigh powder charges without tapping out powder granules from the primer hole/pocket which can add to weight variance of more than 0.05 gr.

Bullseye (.49 disk hole):

• 4.60 gr
• 4.58 gr
• 4.52 gr
• 4.58 gr
• 4.58 gr
• 4.56 gr
• 4.54 gr
• 4.56 gr
• 4.60 gr
• 4.54 gr

W231/HP-38 (.46 disk hole):

• 4.82 gr
• 4.80 gr
• 4.74 gr
• 4.74 gr
• 4.78 gr
• 4.80 gr
• 4.76 gr
• 4.78.gr
• 4.76 gr
• 4.76 gr

Sport Pistol (.49 disk hole): Yes, the new powder metering king with less than .05 gr variance.

• 4.88 gr
• 4.88 gr
• 4.84 gr
• 4.84 gr
• 4.84 gr
• 4.84 gr
• 4.88 gr
• 4.86 gr
• 4.86 gr
• 4.84 gr

 

[Dudedog]

Looks like Sport Pistol meters really well, may have to give it a try.
Of course a powder need to shoot well, but for me, I sure like the ones that meter well also.
What do you think, Faster/slower/about the same burn speed wise compared to HP38?

Unique always shot well for me, I just don't care for how it meters.

 

[Rule3]

Really? I consider powder drop variance of less than .1 gr good enough for match loads and used Pro Auto Disk for my USPSA loads.

So how well does your current powder measure meter?

They all measure "good enough" You apparently are much more "precise" (there is another word) than I am.
Pistol/Revolver and 223/5.56, 308, 30 carbine

0.1 gr of BE, HP38,Unique, Long Shot, etc etc makes no difference to me. If I want 4.8 of xyz and get 4.9 it's all good .
Lee Auto Drum

Lee Pro Auto Disk(no longer use)
Lee Charge Bar(no longer use)
Lee PPM(no longer use)

RCBS Uniflow dual drum (back when they were made better)

All "good enough" to weigh on a Dillon Eliminator (Ohaus) scale

 

[LiveLife]

Sport Pistol ... What do you think, Faster/slower/about the same burn speed wise compared to HP38?

I think Sport Pistol's burn rate is around Titegroup/N320/W231/HP-38.