problems with inconsistent charge weights

[bushmaster65]

OK, here goes,

My equipment is as follows:
Lee auto pro disk powder measure.
Lee safety scale.
Lee progressive press (used manually thus far)

Pertinent background:
Ran My first ever batch of reloads in .38 spcl back in November With 158grn
rnfp using Acurr #2.
The chart said to use disk # .30 for a starting load of 3.6 grn's.
* this barely gave me 3.1 Grns *
I moved to the # .32 disk for an advertised load of 3.8 Grns
* this gave me a 3.3-3.4 Grn charge according to my LSS so I loaded 25 rnds at this charge.*
I then moved to the # 34 disk with an advertised charge of 4.1 Grns which is .1 Grns over the max charge for this cartridge.
* this gave me a 3.5-3.6 Grn charge according to the LSS. So I loaded 25 rnds at this charge.*
*note- I had read that the Lee disk system did have a habit of throwing light charges so I decided to be a little more trusting in the LSS than the disk specs.

All rounds functioned flawlessly at the range with no discernible difference between the different charges.

The problem:
After setting up the scale and press last night, I went to the # .32 disk expecting the charge per my reloading data from Nov.
It threw a charge of 2.8-9 Grns. (not the 3.3-3.4 grns i expected)* I rechecked the zero on the scale. NP
Went to the # .34 disk and got a charge of 3.0-1 Grns. (not the 3.5-3.6 i expected) Rechecked zero on scale. NP
I went up 2 more sizes on the disk and was still only getting 3.4-3.5 Grns and I'm not stupid enough to just accept this gross difference and reload so I stopped. (hadn't even reloaded yet) cleaned up and started inspecting the powder measure and scale.
The scale goes back to zero every time I rechecked it.
The measure functions as it should but I did notice:
1-The measure is tight enough to give an audible squeaking sound when twisted on and off.
2- The rubber gasket/sleeve that causes this squeak, on occasion, was pulling some of the rubber with it, thus occluding the opening ever so slightly but returned to normal position with a very slight twist.
So Tonight I'm thinking of loosening the tension screw for that twist joint and see if that rubber gasket/sleeve isn't my problem.
Any thoughts from the much more experienced?

[jrinne0430]

Interesting, I use the same powder measure with different powder. If my memory serves me right, Accurate #2 is a ball powder and should meter well. During long reloading sessions, I have noticed that sometimes the disk does not retract all the way after a dump. This would require me to tap the top of the hoper to get the disk to “snap” back all the way. You may want to see if the disk is binding on the return cycle.

Also, do you have any check weights you could use to confirm your scale’s accuracy? If you have any lee dippers, you could see if the scale matches the amount the dippers produce.

[Jay24bal]

I have had the same experience when it comes to the Auto Disk throwing a different weight than what the manual says, with most powders I have used. It does not matter if it is a small charge or a large charge, stick or ball powder, the numbers are usually off. And just like you, the actual weight is always lower than their advertised weight. I tend to use their recommended disk as starting point for getting the right number.

That said, I have never experienced a change in the weight thrown by the disks. I always weigh the first couple throws from the Auto Disk and usually a couple in the middle of loading batches of 100 to verify it is still on, and have yet to find a difference of more than .1 in any single throw (usually on the light side). I have never used the double disk attachment and only use it for pistol reloading in 380 ACP, 9mm, 40 S&W, 45 ACP, 38 Special, and 357 Mag.

I agree that you may want to check and calibrate the scale as it may be a simple solution. Or, double check that the Auto Disk is clean and not binding anywhere.

[454PB]

I've been there too, and gave up on "fixed" powder measures for that reason. The Lee measure has never worked well with ball powders, it will constantly bind up as the fine powder particles find their way into the mechanism. Never trust ANY powder measure to throw the same load in a new session. Temperature and humidity changes the volume and weight.

[MEATSAW]

Yes I also deal with leakage from the fine, spherical powders like TAC, Accurate #5, etc. I usually get consistent charge weights once I get it dialed in, but there is definitely leakage. Extruded powders do not leak and are still drop consistent charges. If all powders were shaped like IMR-8208 I'd be a happy camper!

[markr]

Yeah, the disk cavitiy's don't always match the charge weight exactly. You move up and down to get the weight dialed in. Now if the weight is not consistant between throws thats another matter. As suggested eliminate the scale as the cause of the "Flawed' charge by checking it with a check weight. If the scale is correct and you are still throwing inconsitant charges, then it's time to review your technique and equipment:

Is the hopper & cavity sufficiently "Broke in" with powdered graphite, OR repeated false charges of powder to eliminate static cling?

Is the hopper more than half full?

Are you stroking the press the same? As in bumping at top and bottom? Not bumping at all? Are you doing it different each stroke?

[semi_problomatic]

I will also add that it takes a good 10-15 strokes for the powder to settle and start charging consistant. If you're changing the settings after 1 throw you'll be chasing settings and scratching your head for a bit. It's also a good idea to check your charge every 5 or so rounds...

[PA-Joe]

You also have to learn how to double tap the handle on both the up and down strokes to make certain the powder fills the measure and then drops out. The charts are just a guideline and were based upon one batch of powder. Each batch of powder will have a different density. So every time you change batches you have to recalibrate.

[markr]

The important thing is cycling the press all the way up and down. Bumping it, not bumping,....... neither is right or wrong. The important thing is consistancy.

[j357]

Along with consistent technique in cycling, ensure that you have the hopper installed/oriented correctly.

Charge weights do vary slightly from the charts and from session to session. However, it is very easy to reverse the hopper and put it together wrong. The flat side of the hopper base faces the the drop tube - front of the measure. If the hopper is reversed, the curved side blocks the view of the drop tube and the hopper hole is not directly over the disk cavity when the ram is down, causing fill problems. When the ram is up, you should be able to see the disk hole move completely out over the drop tube.

After having a similar experience several years ago I marked mine to avoid future head scratching.

[Don P]

I have come across the same issue with the disk and Acc.#2
Disk #.37 yields 3.6 grain charge and disk #.40 yields 4.0 grain charge.
Its roughly .4-.6 grains different from the charts and data that Lee provides. All I did was place some masking tape on the powder container with the disk # and charge weight written on it. Nothing is wrong with your disk/powder dispensing system. Life is good and carry on. Glad you did the responsible thing and double checked charge weights.

[Unclenick]

Note that powder bulk density (and VMD's) can vary ±6% from lot-to-lot in some powders (see bulk density specs on Accurate's site). This variation means you have to verify the actual charge thrown and not count on any volumetric calculation to be precise.


Bushmaster65,

That 20% change in charge drop is a lot. In addition to the functional checks mentioned above, do a double-check of the beam weight positions on the LSS. I don't have one, but a number of folks on the board have complained it is easy to miss the correct counterweight positions on the beam.

[bushmaster65]

for the advice. I will be back at it tonight and you all have given me a good checklist to go through. I will let you know what I find...thanks again.

Bush

[Gadawg88]

I use the same set-up but have not experienced the variances you are seeing using the same disk hole. I recall the rubber seal on the bottom of my measure was real tight as well at first. Assuming you have it facing the right direction as mentioned above, it may just need some breaking in. You can aid this a bit with some powdered graphite. Work it in with your hands on the top of the disk and the rubber seal on the bottom of the measure. Put some powder in the measure and just throw a bunch of powder charges dumping each back into the hopper as you go. Don't bother weighing them till you have done a bunch, maybe 50 or so, then weigh a few and see if there is improvement. Good luck.

[Don P]

That 20% change in charge drop is a lot. In addition to the functional checks mentioned above, do double-heck of the beam weight positions on the LSS

I doubt two of us have miss adjusted our beam scale. I checked the charge weight on both the Lee beam scale and my digital scale.
The OP and myself have the same charge weight using the same disk number.
Did we both buy powder from the same lot? Maybe, and thats a stretch. My guess is something is up with Lee's data being the OP and myself have found that using the same disk size we get the same charge weight.

[Gunnels]

When reloading reload data is published by weight (grains) and you should reload by weight. However, powder measuring and dispensing is done by volume. With a Lee press it is done with calibrated disk. VDM tables are published as guidelines to tell you how much (volume) of a particular powder will produce how much weight of that powder. You should never reload based upon what a VDM table says. You should reload based upon the weight of the powder dispensed by a particular volume (disk).

VDM table are approximate guidelines when trying to determine what volume of powder will produce a certain weight of powder.

[Unclenick]

Don P,

Your post indicated you matched what the OP threw in November. No problem there. The problem is that it doesn't match what the same disc threw for the OP in January, and that's when a scale setting error became one possible explanation and would need to be checked for.

A quick look at the Accurate site says No.2 has a nominal VMD of 0.102 cc/grain, but that its bulk density varies ±5.5%. That means the VMD might be as low as 0.09639 in one lot and as much as 0.10761 in another lot. That means a 0.32 cc disc could produce anything from just under 3.0 grains to just over 3.3 grains if those numbers are correct. Lee's table says the No.2 VMD is 0.08380, which is smaller than Accurate's tolerance at the low end. Since the powder is made to Accurate's specification, their numbers are going to be the more believable ones.

To me that discrepancy between Accurate's numbers and Lee's numbers suggests either that Lee measured just one lot and did it long enough ago that it's no longer a valid number for current production, or that Lee happened on a lot with a low end VMD for their testing, then reduced it an additional 15% to ensure handloaders without a scale erred on the safe side of actual charge weight. I don't know which.

With any of Western's powders (Accurate and Ramshot) just go to the product description page on their web site, click on a picture of the bottle with the powder number you are interested in and the VMD and bulk density and its tolerance are both available. Note that it give these numbers both for grams and for grains as the weight unit. I believe the grain unit numbers are on the lower row in all instances. Just read the units to check and realize that while they differ from Lee's numbers, it won't be by more than ten or twenty percent. If it's several times that, you've probably read off the wrong line.

[Pond, James Pond]

All that sounds SOOOoo familiar.

I had the same problem with my stick powders from VV. First the charge weight was never what I expected: always lower than what was listed. Then the first few charges of any reloading session were even than that for the first half dozen throws.
Almost as if the measure had to be primed first.

Totally nuts....

So much so that I ditched the auto disk and went to batch reloading.

I am in the process of ordering a Lee Perfect Powder measure to use instead. It sounds like you have advice to go one, but for me, using the scale was just easier, despite the far greater time needed. Perhaps the Lee PPM will do the trick.

I hope you find peace with you auto-disk. Very frustrating when it does not go your way as you would expect it to.

[ddc]

Fairly new reloader here with a Lee Pro Auto Disk setup and a Lee Classic Turret.

I was about ready to give up on the Auto Disk. A series of reasonably close throws might occur. Then I would seemingly get light throws by about .2 to .4 grains and sometimes more. (Using Ramshot True Blue and Silhouette, both small grained (TB especially) spherical powders.)

I finally discovered things about this setup that really helped to get repeatable throws: You have to weigh your throws following a complete revolution of the turret just as if you were doing some actual loading. If you just weigh with the turret in one place with the Auto Disk over the ram you will get successively lighter throws. I have to admit that with 20/20 hindsight I’d read about this but it never sunk in until … it finally sunk in. LOL.

I’ve done several tests to verify this. Using the .43 disk opening slightly drilled out to give me a hopeful 5.5,5.6 grains of Silhouette the following sequence might occur:

1. Run the turret through the cycle several times and then throw the powder. I’ll get something in the desired 5.5,5.6 range.
2. Leave the turret in place and throw another. The weight will be slightly lower, say around 5.45.
3. Leaving the turret in place do another throw. The weight will be slightly lower than the previous, say around 5.4.
4. Usually about the 3rd or 4th throw without any turret motion and the throw will stabilize, say around 5.35,5.4.

If you then run the turret around it’s cycle again and throw another charge the measurement will be back at 5.5,5.6 grains.

If I am careful to only weigh following at least one complete turret rotation then I am now getting repeatable measurements.

I’ve also noticed the tendency that James Pond refers to where it seems as if the system needs to be “primed”. Almost like it needs to be warmed up first.

Now whenever I fire up the press, or whenever I start over after having let it sit for a while, I run 5 to 10 charges through the Auto Disk before I start measuring and any subsequent loading.

If I do both of the previously noted operations I can get repeatable throws with the Auto Disk.