drum powder measure drifting?

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labnoti

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I normally only reload one or two hundred cases at a time, but yesterday I reloaded almost 1200. My charge weight was 10.00 gr. and my Lee Auto Drum powder measure usually throws charges with this powder +/- 0.06 gr. I checked it four or five times before I started loading and it was throwing charges like 9.94 gr to 10.02 gr.

After almost 400 rounds, I checked it again. It was throwing 9.6 gr. My mistake for not checking sooner. Fortunately, it drifted down rather than up. I wondered if the near-empty powder hopper was putting less pressure on the drum, but after I filled it to the top, it was still throwing light charges. The powder is a coarse ball powder that should behave well. I don't think it packs down or fluffs up like a large flake or fine ball powder. I screwed out the adjuster and carried on. I checked the charge more frequently after that but found I had to adjust it twice more before I had loaded them all.

I speculated that maybe the inertia of the drum rotation was gradually knocking the adjustment in, but I'm not convinced of this. I'll have to put white marks on the drum and screw and see if it's drifting there or if the volume of the chamber is not changing but something is changing with how it fills.

Any other ideas why it might have done this or what else I should look for?
 
labnoti said:
I normally only reload one or two hundred cases at a time, but yesterday I reloaded almost 1200. My charge weight was 10.00 gr. and my Lee Auto Drum powder measure usually throws charges with this powder +/- 0.06 gr. I checked it four or five times before I started loading and it was throwing charges like 9.94 gr to 10.02 gr.

After almost 400 rounds, I checked it again. It was throwing 9.6 gr. My mistake for not checking sooner. Fortunately, it drifted down rather than up. I wondered if the near-empty powder hopper was putting less pressure on the drum, but after I filled it to the top, it was still throwing light charges. The powder is a coarse ball powder that should behave well. I don't think it packs down or fluffs up like a large flake or fine ball powder. I screwed out the adjuster and carried on. I checked the charge more frequently after that but found I had to adjust it twice more before I had loaded them all.

I speculated that maybe the inertia of the drum rotation was gradually knocking the adjustment in, but I'm not convinced of this. I'll have to put white marks on the drum and screw and see if it's drifting there or if the volume of the chamber is not changing but something is changing with how it fills.

Any other ideas why it might have done this or what else I should look for?
Click to expand...
Check the rotation of the drum. If the drum is not returning consistently after each charge, you will get inconsistent powder drops. The drum cavity needs to line up with the top powder channel to fill the cavity. If an misalignment happens, the cavity may not fill completely.
 
I took the bottom of one of the mini coke cans and poked a few holes in it. I tied it to a piece of fishing line, which I leave hanging out of the top (so I can retrieve it). I pour my powder in, and it works like a dam to control the amount of pressure on the bottom of the powder pile. It works fairly well for me for more consistent throws.

The secret to consistency is the same of everything: alignment, pressure, amount, mounting, length of cartridge, even the spin of the turret or rotation for a progressive press. The closer you can make those to being the same, the better off you are.
 
Quick math tell me that is 12000gr which is almost two pounds. How many times did you refill the hopper?

Even using Hodgdon HP-38 powder my drum stays pretty consistent. If I start drifting I empty the measure and open the drum and quickly blow it out. At one time the thumb nut loosened up and I started getting inconsistent drops as the drum wasn't rotating fully.
 
My uniflow is kinda fussy about how much powder is still in it, so I keep it over half full, with a baffle, and it's fine. and for whatever reason, the knurled nut that locks in the adjustment screw really needs to be cranked on there, or else it will eventually loosen up and let the adjustment wander.

so, even with something like H110, that drops super consistently, I weigh each 10th drop at least, to be sure it's all still square.
I hate pulling apart ammo, because of a shred of doubt.
 
I find my drum style powder measures do drift a little bit over time. It does not seem to matter as to manufacturer, I have a Uniflow, Redding 10-X and Hornady L-N-L.

To help, I use a baffle in all of them.

Also, I have a micrometer adjusters on all them and record the setting for each particular load. I set the adjuster then cycle 25-30 charges through the powder measure to settle the powder column before I begin to fine tune the powder charge.

I check weigh charges frequently during the early stages of a the reloading session but I find the variability settles down as the session continues.

This works for me. I'm sure other methods would work as well.
 
I filled the hopper at least three times. I emptied a pound bottle and refilled it from an 8-pound bottle.

I took the expander off my powder measure and replaced it with a short rifle thing. I expand after I resize. By doing it this way, I can adjust the drum rotator so I get full rotation, which would otherwise have caused excessive expansion/flaring. The plastic armature isn't as precise as I would like and it flexes. I suppose it would cost an order of magnitude more to have those parts precision-machined.

Fortunately, this was a batch with light-weight, high-velocity handgun bullets, and the extreme spread of powder masses should only result in a maximum of 1/2 MOA difference POI. But I definitely want to do better on future runs, especially if I'm doing an intermediate rifle cartridge.
 
I use a baffle positioned about 1/4 way up the column. Keep the column at least 1/2 full. Weigh every 10th drop from my lyman 55. Knock the drum twice at the bottom of the drop. Flip the knocker twice after returning the drum to the top.

I got the template for the baffle off the net, has many different patterns for different sizes.
 
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splattergun said:
I keep my powder measures, all of them, no less than 1/2 full. It's a common practice among many reloaders.
Click to expand...
Yep, I keep mine topped off so the powder is above the baffle, the charge weight will change from full to almost empty if you don't, some powders being worse than others.
 
cfullgraf said:
To help, I use a baffle in all of them.

Also, I have a micrometer adjusters on all them and record the setting for each particular load. I set the adjuster then cycle 25-30 charges through the powder measure to settle the powder column before I begin to fine tune the powder charge.
Click to expand...
Same here.
 
You did not say what specific powder or caliber not what device you use to weigh???
To me in a handgun the variance is insignificant to lose sleep over. But YMMV
 
labnoti said:
My mistake for not checking sooner.
Click to expand...
When you use a hand operated powder measure, there are some items you can physically add to the measure to aid you, but the greater bulk of the result rests squarely upon the user's technique in the operation of the powder measure.

► Of the things you can, should, or must add are:
1. A powder baffle (Click Here and make one)
2. O-rings or wave washers to keep the adjustment lock nut in place
3. Using a weighted base, or somehow constraining the powder measure to stay in one place

► Everything else is the user's technique, the absence of which is known as "operator error". You've already owned up to the mistake, but what I will do is encourage you to do is to NOT miss the lesson. Write it down. Maybe you should have a page in your reloading notebook where you refine your powder measure technique. A list of procedures to incorporate whenever you use your Lee Auto Drum. A list such as...
• Keep the hopper at least 1/2 full
• Never attempt adjustment until at least 10 drops have been completed. (E.g. Give the volume of powder time to settle.)
• Check the output every 100 drops
• Since you KNOW the measure includes some variation, use an averaging scheme to make adjustments. (E.g. If you want 10gr drops, then adjust your measure to drop 100gr in 10 consecutive drops. By this the "average drop" will be much closer to 10gr than any individual drop.)

Hope this helps.
 
rfwobbly said:
• Since you KNOW the measure includes some variation, use an averaging scheme to make adjustments. (E.g. If you want 10gr drops, then adjust your measure to drop 100gr in 10 consecutive drops. By this the "average drop" will be much closer to 10gr than any individual drop.)

Hope this helps.
Click to expand...


The method of using an "average" is a falsehood regardless of the powder measure used. It is just that "an average"

You could drop 8 times with 10 grains then one could be a 0 and then one with 20gr. Yes that is exaggerated but several drops could be over a little and some under but as an "average" it comes out looking good

There is no need for a baffle in the LEE, as the metal "neck" of the hopper always has powder in it. The weight of the hopper powder is only on the SMALL hole in the base of the hopper. Be sure the hopper is turned FULLY to the ON position
 
I doubt it's the adjustable part screwing itself in and making the volumetric metering space smaller.

Far more likely is some change in the rotational component. I have had my Auto Drum throw light charges where a bit of powder has leaked into the space between the rotating cone and the housing and caused a little binding. The drum didn't rotate quite far enough to fully dump every granule. Cleaning the AD fixed it. You can also get similar variations if the powder drop/expander die backs out a little bit and you were just at the threshhold of full rotation on the drop before it backed out.

Another possibility, if you are in a poorly-climate/humidity-controlled area, is that the humidity of the powder is changing and taking density with it.
 
I get AR at times with weighing my powder charges. Though because I an doing small pistol charges a variation of +/- .2gr can be a huge swing. For some reason I can't seem to get past 25 drops or so w/o having the urge to weigh check. If things are jumping around I can find myself weighing every 10th one. Yes there have been many times that I have dumped a charge back in and recharged the case.
 
I have the Lee drum and a Redding BR-30 drop with baffle (drum).
Both are going to go hinky somewhere between full and about 30 drops left. I use the Redding. I make sure it is about 75 % - 100-90% full when using it.
That being said, I weigh every drop before filling the case with a Redding #2 beam scale. I don't think I am being anal in doing this but I only shred paper at 100-200 yards and that .20-.40 inch difference means having a good day and a bad day.

It also makes a difference in weather conditions and the type of powder you are using. Varget is quite different than CFE-223 in drop variances.
 
Another mountain out of a mole hill.
Unknown powder, unknown caliber, gun, unknown scale all for .06 grain variance out of a 10 grain load.?
all for "hypothetical"??
"Fortunately, this was a batch with light-weight, high-velocity handgun bullets, and the extreme spread of powder masses should only result in a maximum of 1/2 MOA difference POI. But I definitely want to do better on future runs, especially if I'm doing an intermediate rifle cartridge."

At what distance, using what method?
 
I think that a fact of life is that powder measures will drift. Even with baffles and consistent operation somehow things will change. But with all of these imperfections we still manage to make decent ammunition throwing charges.

One thing I have learned is to weigh charges periodically and tweak if necessary.

I loaded some .223 with 24.0 of Rl15 the other day with a Uniflow that was previously right on for this charge. Once that it settled in it was closer to 23.5. How is that possible?
 
Consistency comes from technique and powder column "setteling". I do not have my measure attached to my bench, but isolated on a smaller bench. Any bump or bang to the bench from press operation causes setteling in the column. My charges got morr consistent aftet doing this.
 
Rule3 said:
The method of using an "average" is a falsehood regardless of the powder measure used. It is just that "an average"
Click to expand...
True, you need to know what the max it might throw if using an average, which means you need to throw a lot of charges.

I use an "Average" for middle of the road/plinker loads/under max loads, but I have thrown enough charges I know what the max is and know it is safe.

If I am at or near max I do not use an "Average", I use the max it will throw and log that powder charge vs an average. I log it as "Max, not Average" next to the powder weight. If I don't have that by it, I know it is an average.
 

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PWC said:
Consistency comes from technique and powder column "setteling". I do not have my measure attached to my bench, but isolated on a smaller bench. Any bump or bang to the bench from press operation causes setteling in the column.
Click to expand...
Yep, I try to be consistent in my speed on the handle up and down, and try to "bump" the handle at the down stroke on my LNL the same each time. I do not size while loading so that really makes it much easier to do this.
 
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