Tweaking Lee pro disc measure

J

jetinteriorguy

New member
I really like using the disc measure for pistol loading, but every once in a while the perfect load is in between two cavities. I work up my loads with the perfect powder measure then see if a disc will throw the appropriate amount. Well today I figured an easy way to make a cavity bigger that's simple, easy, and very affective for accurate throws. I just chamfer the top edge with my old RCBS chamfering tool until it throws the correct amount. So far I've only done this using Bullseye, but I'd imagine it would work with most pistol powders. I'm going to play with this a little more with my other powders and loads and will report back.
 
As long as thining the edge that much doesn't start a leak, it is a good idea. You could also use a T-handle-type taper reamer if you didn't want to thin the lip as much.
 
So far I have done it to two of my pet loads. One using Bullseye and one using 700X and it has worked pretty good. I do like you're approach Nick and it does seem like a more gentle taper would work better creating a better funneling effect for a more consistent drop. I think I'll see about picking up some reamers and give it a try.
 
Jetinteriorguy, a more "common" method, at least the one I've read about before and used successfully myself, is to use a slightly larger chamber in the disk to the load you desire, drill and tap a hole into it from the side, and then place a screw into it that you can screw in and out to adjust the effective cavity size. One can really fine-tune a larger load or even a really small handgun load that way. I use a brass screw in mine for precision. And you can readjust any time and no danger of going "too far" and making it unusable.
 
I am familiar with that method, the only problem I have with that method is the possibility of powder getting hung up on the screw protruding into the cavity. I don't know if this is a problem, but it's just the way I've looked at it and dismissed the idea. I know another thing is to put some epoxy in the cavity as well and then just sand away until you get the desired results. Seems like a pita to me. So far in the limited times I've just used the chamfering tool it has worked great, just don't go overboard with it and slowly work your way up. I have another tool I'm going to try, it's a reamer from the old days of racing rc cars. It was designed to ream the mounting holes in the car bodies to fit the mounting posts. It has a much more gentle angle than the chamfering tool. I'm not too worried about going too far removing material, I have so many of these discs on hand I can waste a couple. Plus I think you could always drop down an extra size and just take off more material to get back to where you need to be. I'll keep reporting on various powders and methods as I go along.
 
I have a disk that I did this to also. Like you say these disks are so cheap to buy and are so plentiful that if I ruin one I am not out much.

As a note, if you actually measure a cavity you sill see that they actually have a reverse taper in that they are wider on the bottom than on the tip.

On one disk I actually tried a twist drill in a drill press to open it up and it turned out horrible. Drill did not cut a clean hole in the plastic.
 
Interesting on how the holes are reverse tapered. I tried a load for my 148gr wadcutters using Clays and the pro disc was a no go. At least in the .34, .37, and .40 size holes the powder dropped very erratic. I then went with HP38 and it functioned great.
 
I have one of those disc measures.
That is why I use ONLY adjustable measures like Lyman #55 and two PPM's, and now a new auto drum.
PPM is $25.
I was never all that comfortable with bushing measures in shotshell loading, and got an adjustable charge bar there, too.
 
I know what you're saying. I haven't used one of these in probably three or four years. But I was bored and my little brain started thinking and well, we all know how that can lead to trouble. So I thought I'd play with them since I have two of them just laying around. For certain pistol loads with certain powders as long as they can drop the right charge they are very consistent and very convenient to use. So once I work up a pet load with my normal powder dispenser I'll first check if the powder meters ok in the closest cavity size and if it does then just tweek the cavity to drop the precise charge. It gives me something to do and at the same time utilizes equipment that's just sitting around doing nothing. I too have a couple auto drum measures, a Lyman 55, a Lee Perfect Powder measure, and the Improved Perfect Powder Measure. I work up all my loads with the new PPM and then use the removeable drums preset for all my rifle and some of my pistol loads. I use the drums in the Auto Drum for pistols and use the drums in the new PPM for my rifle loads.
 
jetinteriorguy said:
I really like using the disc measure for pistol loading, but every once in a while the perfect load is in between two cavities. I work up my loads with the perfect powder measure then see if a disc will throw the appropriate amount. Well today I figured an easy way to make a cavity bigger that's simple, easy, and very affective for accurate throws. I just chamfer the top edge with my old RCBS chamfering tool until it throws the correct amount. So far I've only done this using Bullseye, but I'd imagine it would work with most pistol powders. I'm going to play with this a little more with my other powders and loads and will report back.
Click to expand...

I had the same problem. Unless you are using very small powder charges, I highly suggest using the Lee Adjustable Powder Charge Bar. It works incredibly well with all pistol powders I've used. :D
 
I use Lee Autodisk powder measures on all the turrets for my Lee Turret Press. I currently have four turrets set up, ready to swap out for when I want to change what I'm loading. That said, I have no interest in customizing even one hole in one disk to achieve the "perfect" load for one particular caliber, bullet weight, powder type, and velocity. I would go nuts buying, modifying, and trying to keep track of disks.

For example: I load for handguns, and except for some cowboy loads using Trailboss I load everything with Winchester 231/HP38. In .45 ACP, I go from 230-grain round nose to 200-grain semi-wadcutters to 185-grain round nose. In 9mm I may load a 100-grain round nose, a 115-grain round nose, or either of two 124-grain hollow points. That's potentially seven different apertures just to cover two "calibers" with one powder.

Thanks, but no thanks. Too complicated for me. If one of the standard apertures gets me a mid-range loading for the caliber and bullet weight, that's good enough for me. If I were shooting bullseye, it might be a different story. If I were shooting bullseye and I were competitive, it almost certainly would be a different story ... although, even then, I think round-to-round consistency is probably more important than achieving some particular velocity to the last digit of feet=per-second.

For those who must dial in loads more accurately that the pre-set apertures allow, Lee offers the Adjustable Charge Bar. I have one, but I don't use it because I haven't (yet) found a need for it.

https://leeprecision.com/adj-charge-bar.html

It's cheaper than a box full of modified disks, and you only need to buy it once. It's calibrated, so it's repeatable. And if you make a mistake, it's reversable.
 
I do have the adjustable charge bar as well, but I don't care for it. I have two of the auto drum measures and they work much better. The disc measures are just something I'm messing around with since I already have two of them on hand and a bunch of discs so I'm not investing a dime, just finding a use for what I already have on hand. The whole point of my post is to offer an idea for making them more useful to anyone who is interested.
 
That taper inside the discs is a relief angle. They are common in molded plastic parts because they make it easier, or in some cases possible at all, to get the finished parts out of the mold or to withdraw pins that form holes.
 
I too use the disk measure and load 4 pistol calibers; 380, 9mm, 38Spl, 45acp. I also use 4 different powders; AA#2, AA#5, HP-38, Ramshot Silhouette. With these different calibers and powders I too use many different bullets and I have to say that with the Disk measure there was only one combination where I could only come up with 1 load and that was with the HP-38 using a 100 gr plated bullet in the 380. With all others I was able to come up with at least 2 different loads, that being either a low/start and medium load or a medium near max load. Then with a couple I was able to come up with a start, medium, near max load.

Now with my shooting habits and style with pistols I have found that a couple of grains more or less is not going to make a significant change to my load. With this I have found a load that I can take a disk, put it in the measure and drop a very usable load and is very much repeatable.

When I load using the Disk Measure I use the disk cavity number on the label for powder weight. So I suppose one could honestly say that I am volume loading and not weight loading.
 
jetinteriorguy said:
I do have the adjustable charge bar as well, but I don't care for it. I have two of the auto drum measures and they work much better. The disc measures are just something I'm messing around with since I already have two of them on hand and a bunch of discs so I'm not investing a dime, just finding a use for what I already have on hand. The whole point of my post is to offer an idea for making them more useful to anyone who is interested.
Click to expand...

What about the LACB keeps you from using it? It works great for me. Seems to me that you have your solution in-hand. Enlarging the disk hole diameters is only a temporary fix as the density of a powder will vary from batch to batch.

Regarding the auto drum measure, have you used it with very fine ball powders such as H110, and if so, does your measure leak? :eek:
 
It's been a while since I've used it, but if I recall correctly the LACB just didn't work with some of the powders I use. Plus, it still needs to be adjusted for every load. Or maybe once I got the drum measure I just didn't need it anymore. But as I've already stated a couple times, I'm just sharing an idea that is something that makes a tool I already have a little more versatile for anyone who is interested. As far as lot variances and how that affects a load, in my mid power pistol loads I don't think there will be enough differences to worry about, at least that's been my experience in the last 36 years of loading for pistols. I only shoot 7-12 yards, any long distance shooting for me is pretty rare anymore and for that I would use heavy magnums that I load special by weight checking each powder drop. Oh, and yeah the fine powders did leak pretty bad at first, then I took each drum with some coarse polishing compound and put them in the housing and just rotated them back and forth lapping them for a much better fit which eliminated most of the leakage. I also have pretty much eliminated those powders from my inventory as they were used up so no more issues.
 
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