Noted Charge Differences between Pro & Auto Disks

[Ranch Dog]

My Load-Master is up and running delivering 9mm Luger ammunition, complete, with priming and bullet feeding on the press. I haven't been too happy with the accuracy performance at the range as compared to that delivered with the same load being prepped on the turret press. I'm seeing point of impact variations that are too great to be acceptable. At 3 yards my pistol, a Taurus PT111 Pro, will and should be a ragged hole shooter with all the rounds touching the first hole. Everything about the L-M produced cartridge is perfect, bullet runout is nil so I'm suspecting velocity variations but for the last two weeks we have been under flooding conditions so I don't have the weather to set up the chronograph to check.

What I did last night was look at the powder delivery system used on the L-M, the Pro Auto Disk, as on the turret I use the Auto Disk. I've noted in other posts that I prefer it to the Pro as I've simply seen more consistent, measured, results from the original design.

One thing that I do with any Lee device is establish the VMD for the specific powder. As an example, my experience has taught me that the Adjustable Charge Bar will not deliver the same VMD as the fixed cavities. If you are interested in specific grain charges set up with the cc settings the device offers, the VMD will be different between the Adjustable Charge Bar, dippers, disks, doubled disks, Micro Disk, and Perfect Powder Measure. There are also slight differences in VMD to deliver a specific charge based on the press used; Load-Master or Turret, as the "bump" experienced during cycle causes the measuring chambers to load the powder slightly different. I record all this stuff to make dropping charges easier.

The primary delivery system for the L-M is the Pro Auto Disk and that is how my press was set up. My desired charge of 5.8-grains of HS-6 was not possible with the fixed disk system, that charge falling between a .40 and .43 cavity, so I've been using the Adjustable Charge Bar set at .38 to drop the charge.

I dropped ten charges using the ACB and then placed a fixed cavity disk in the PAD and measured the results. Those results where terribly disappointing. I replaced the PAD and the AD and measured ten charges. The results were what I I've experienced with the simple unit in the past.

HS6_powder_drop_variation.jpg

Looking at the .4-grain ES that the ACB has been dropping explains a lot. That probably is create velocity ES between 70 to 75 FPS. Since yesterday afternoon we have been receiving a heavy tropical type rain, probably 3" overnight, so I'm not sure that I will be able to use my range for a day or two. The next order of business is to try a string of cartridges from Auto Disk to see if this device get the pistol back on track.

So for now my L-M has the Auto Disk riding on it.

LM_AD.jpg

[akuser47]

Wow that's alot of variation I wonder if the expensive redding unit s would have same variations. They are renowned for accuracy in rifle comp. Loaders. Just brain storming as I'm sure u may find a solution with the lee. Thanks for the update.

[Ranch Dog]

Wow that's alot of variation I wonder if the expensive redding unit s would have same variations. They are renowned for accuracy in rifle comp. Loaders. Just brain storming as I'm sure u may find a solution with the lee. Thanks for the update.

Well the solution for me is to just use the basic Auto Disk. I ran another charge test this morning before starting the press on a loading run. The results were the same with the AD, very tight.

I did suspect that the wiper on the Pro was creating an issue but this hopper is relatively new. Why I suspected it was the powder left behind once the hopper was removed.

PAD_ACB_powder.jpg

As you can see, this is the Adjustable Charge Bar, and it has consistently left behind a bit a powder every time I have shut the dispenser off to dump the powder. I do cycle it a number of times to empty the charging chamber below the shut off. I suspected the wiper until I tried using the single disk. It never had any powder left behind so that rules out the wiper. Honestly, I've always seen a bit left behind after using the ACB.

I have a Prairie Dog baffle in the hopper, I might remove it and see what the differences are without the baffle. I also have the Titan baffle and might try it as well.

[62chevy]

My limited experience with ACB is the same as RD's leaving powder behind. Not sure the Titan baffle makes any difference but then I've only used it a few times and not sure what to look for.

[Ranch Dog]

Well... the Auto Disk dropped load shot well. A ten-shot group of 1.301" at 21'.

The velocity was a little bit whacked though.

Average FPS = 879 (which was a bit low for the load?)
SD = 30 FPS
ES = 77 FPS

I might go ahead and load ten from the Pro Auto Disk just to see what changes to the SD and ES there are.