Lee perfect powder measure

[chukarmandoo]

I am posting this thread to explain what I've found in regards to this loading tool. Take it for what its worth.

I've been using the PPM for several years now and my understanding of it has not been very good until this last year.

To begin with, I have used it like most reloaders do, adjust it close to the desired charge and then trickle.

Well after hours and hours of trying to work out a method to drop or through accurate charges I've come to have a better understanding of how this all works.
First off, for a company to state that it is The Perfect Powder Measure, there must be some validity to the claim.
When you measure by volume it is a whole new game. And I believe it is more accurate in the big picture than using scales. A bold statement for sure but volume is always the same with powder but weight can and does change.

[chukarmandoo]

I have to post this way because my computer doesn't work right, sorry.

So to continue; here's what I've found. 1- Don't underestimate the PPM. 2- This is a big one, Understand that powder can change per lot. 3- Follow the instructions and use the chart in the back of the manual for the volume to weight ratio. It is the only way to obtain the correct weight of a particular type of powder. 4- don't tap the measure or jiggle it. this is definitely the wrong approach to using this tool. 5- Use slow motions when operating the handle. This lets the powder fall into the tube very consistently and dump the charge slow. This will greatly reduce the chance of the powder getting clogged as it falls into the case.

[chukarmandoo]

Again I apologize for the way I'm posting this.

6- If you are sure that you have set up the unit correct and the volume is right dump a few charges. Note; do not let the powder granules be cut (you can feel this when it's going to happen). Back the handle up just a touch and then move forward, it should clear. If you cut the granules you can damage the rubber wiper in the unit.
7- After you have dumped a few charges start to weigh them and take note as to what is happening between the too. If your charges are coming out close to the weight, for me its .1+/-, then I'm good to go. If it is way off and everything is setup right then I adjust the scales to see how much the powder is out of spec! I do not adjust the PPM!

Be forewarned, it takes a lot of trial and error to find out how to be consistent in throwing charges but it is worth it in the long run.
Also if you take it slow, the key word here is slow, you can use all kinds of powder with success. The powders I use the most are H4350, RL15, and Retumbo.
Also a note; Once you get everything setup and working throw and weigh each load for a while till you can become consistent.

[m12lrs]

Yeah

Throwing.charges is.an art. Consistency is the key. Practice practice practice

Fastest way to charge.cases by far.

[darkker]

You got lost in the theory there Chukarmandoo, assuming you are actually looking at volume; what you are doing isn't volume, its still weight. If you want to use a volume device for a weight, then you seem to have found a good enough method. If you want to use it as intended, then here are some thoughts.

1 - Indeed :)
2 - Almost, not that it CAN, but that it DOES change.
3 - Charts are nice, but remember #2 just above. Do your own VMD for EACH bottle of powder. The weight portion is to establish a reference point only, VERY few powders will list their nonimal variances for BD, so there is no "right or wrong".
4 - Doesn't matter as long as however you do it, you always always do it the same.
5 - I agree, but the main take home point should be consistency.
6 - Unless they changed it, there is no rubber wiper, it is all just plastic. And cutting extruded kernels doesn't matter, as it is the relative geometry(including perforations) that controls the burning rate. The total area will change when you cut kernels, but not the relative geometry.
7 - Again, if this is about getting to a weight, fine and dandy. But that is incorrect if you actually want to load by volume.

Remember that 99% of the powders you buy do not list nonimal variances(BR & BD). Extruded powder has it's burning rate controlled by geometry, it's weight is only a function of the total energy(BD). The weight taken off of a sample of charge volumes is for a reference point ONLY, it isn't a hard and fast reference point. If you want a more consistent result (from extruded powder only) from your reloads, then you need to control the burning rate. Weight will not do this, only controlling the volume will. A controlled volume in the case fill will also negate burning rate shifts because of differing case volumes. Weight alone only controls the total energy content in the extruded powder, it does not control how quickly it burns, and thus the pressures encountered.

[m12lrs]

You got lost in the theory there Chukarmandoo, assuming you are actually looking at volume; what you are doing isn't volume, its still weight. If you want to use a volume device for a weight, then you seem to have found a good enough method. If you want to use it as intended, then here are some thoughts.

1 - Indeed :)
2 - Almost, not that it CAN, but that it DOES change.
3 - Charts are nice, but remember #2 just above. Do your own VMD for EACH bottle of powder. The weight portion is to establish a reference point only, VERY few powders will list their nonimal variances for BD, so there is no "right or wrong".
4 - Doesn't matter as long as however you do it, you always always do it the same.
5 - I agree, but the main take home point should be consistency.
6 - Unless they changed it, there is no rubber wiper, it is all just plastic. And cutting extruded kernels doesn't matter, as it is the relative geometry(including perforations) that controls the burning rate. The total area will change when you cut kernels, but not the relative geometry.
7 - Again, if this is about getting to a weight, fine and dandy. But that is incorrect if you actually want to load by volume.

Remember that 99% of the powders you buy do not list nonimal variances(BR & BD). Extruded powder has it's burning rate controlled by geometry, it's weight is only a function of the total energy(BD). The weight taken off of a sample of charge volumes is for a reference point ONLY, it isn't a hard and fast reference point. If you want a more consistent result (from extruded powder only) from your reloads, then you need to control the burning rate. Weight will not do this, only controlling the volume will. A controlled volume in the case fill will also negate burning rate shifts because of differing case volumes. Weight alone only controls the total energy content in the extruded powder, it does not control how quickly it burns, and thus the pressures encountered.

seems to me that weight would vary in a certain volume of powder according to the density of the powder contained in your volume measure. A perfect example is dumping a charge into a case with a short drop tube and a long drop tube. Another example is throwing a charge into a case and then tapping it a few times.

If you are using volumetric measure how do you take the variations in densities between loads into account. In the two examples above the volumes would be quite different but the weight would remain the same.

[darkker]

1) seems to me that weight would vary in a certain volume of powder according to the density of the powder contained in your volume measure.
2) A perfect example is dumping a charge into a case with a short drop tube and a long drop tube. Another example is throwing a charge into a case and then tapping it a few times.
3) If you are using volumetric measure how do you take the variations in densities between loads into account. In the two examples above the volumes would be quite different but the weight would remain the same.

Yes the weight will vary, but we need to correct this line of thinking to keep things on the correct path.
1) That is correct, but it doesn't matter; more on that in a bit.
2&3) That example has a greater impact on the volume, a weight change is only a side effect. Back to the main point of being consistent. Neither long/short is "better" inherently, they just produce differing results. But you can't compare them as the same. Would be like comparing a scale calibrated to +/- 1#, Vs. +/- 0.000 oz. One may be more appropriate for any given application, but that doesn't automatically make the other "bad"; simply less appropriate for a given task.

Hopefully this will make things more clear:
When Extruded(Extruded ONLY) powder is designed and built, it has whatever nonimal allowable variances in terms of energy and burning rates. The important part of this is that the relationship of Energy-to-burning rate is VERY tightly controlled.
So if a particular lot of powder was on the more energetic side of the tollerance, during extrusion the geometry would be such that it would burn slower than typical. So in the end the results would turn out as desired. Alternatively if the powder was a little light on energy, it would be set to burn faster than "typical"; again the end results would produce what was desired.
So if you only control the charge weight you lose control of consistent case fill, this will cause burning rate shifts on its own but also ignores the burning rate aside from case fill. If you control the volume, you are not only controlling case fill, but controlling the burning rate aside from case fill. If the burning rate is controlled, the energy differences are already accounted for.

Now as to how much this difference affects results is certainly arguable. But for those who think that 0.1gr differences are "that important", I challange them to actually test it. There was another member here who recently followed by advice and tested this very thing. What he found, and I haven't followed that thread in quite some time, was that the previous notion of having to maintain 0.1gr loads, in reality isn't the case. Especially when you don't know what the nominal variance is. Can't control what you can't define.

Again, neither system is "wrong", but they are not the same! The powder manufacturers design, build and load around volume. Weight is an invention of the handloader, since accurate scales have been around since the romans. Look in old load manuals from Olin(one example only) when they were still in the biz, most of the data was in volume. Weight is ONLY needed as a reference point for the handloader who has data in weight. But they aren't connected. The PPM is about the only volume system that has relevant volumetric calibrations, other systems only have hash marks that don't tie to anything volume wise.

When a Pressure Trace II system was purchased and we could actually *accurately* measure pressures in our rifles, it was amazing how many things I thought I knew; that I actually had very little understanding of. Think brand X has conservative load data, nope, simply a function of how much variation there truly is in lots of powder!

Cheers!

[chukarmandoo]

Darkker this is what you told me on another thread 11-9-2013;

Go buy yourself a copy of Richard Lee's Modern Reloading Vol. 2. An excellent discussion on it.
For EXTRUDED powder only, burning rate is VERY closely tied to bulk density. Geometry is what controls the burning rate. Volume accounts for changing BD & BR. Weight only addressees the BD, and leaves you subject to a moving BR.

Ball powder is an entirely different animal. Due to consistency, you can certainly get away with volume (I have been for a VERY long time). However, if you are the toe that likes to run nuclear pressures as long as the bolt doesn't seize... Weight is more appropriate for you, when using ball powder.

Well I took your advise then and have read the book and I think I'm using it correct?

[darkker]

I recall that thread, just couldn't recall that it was you.

You are close, but missing the vision somewhat. Referencing to 0.1gr is missing the point of volume, and really chasing weight.
There is a reference to weight, simply to have a starting point, but there isn't a direct tie to it, unless you are sure of the nominal BD, which we can't be.
Also cutting kernels doesn't matter, the relative geometry doesn't change appreciably.

You seem to be on a nice path, just work on consistency. Consistency will keep volume the same, don't fret over the weight wiggles.

[chukarmandoo]

You got lost in the theory there Chukarmandoo, assuming you are actually looking at volume; what you are doing isn't volume, its still weight. If you want to use a volume device for a weight, then you seem to have found a good enough method. If you want to use it as intended, then here are some thoughts.

1 - Indeed :)
2 - Almost, not that it CAN, but that it DOES change.
3 - Charts are nice, but remember #2 just above. Do your own VMD for EACH bottle of powder. The weight portion is to establish a reference point only, VERY few powders will list their nonimal variances for BD, so there is no "right or wrong".
4 - Doesn't matter as long as however you do it, you always always do it the same.
5 - I agree, but the main take home point should be consistency.
6 - Unless they changed it, there is no rubber wiper, it is all just plastic. And cutting extruded kernels doesn't matter, as it is the relative geometry(including perforations) that controls the burning rate. The total area will change when you cut kernels, but not the relative geometry.
7 - Again, if this is about getting to a weight, fine and dandy. But that is incorrect if you actually want to load by volume.

Remember that 99% of the powders you buy do not list nonimal variances(BR & BD). Extruded powder has it's burning rate controlled by geometry, it's weight is only a function of the total energy(BD). The weight taken off of a sample of charge volumes is for a reference point ONLY, it isn't a hard and fast reference point. If you want a more consistent result (from extruded powder only) from your reloads, then you need to control the burning rate. Weight will not do this, only controlling the volume will. A controlled volume in the case fill will also negate burning rate shifts because of differing case volumes. Weight alone only controls the total energy content in the extruded powder, it does not control how quickly it burns, and thus the pressures encountered.

Remember this is the internet and people can read into it with different tones. So just to be clear I'm not being a wise guy here.

number 3- I do my own VMD as per the book. And they are always different than the numbers listed example: 4.20 cc should = 58.25 grains weighed of a particular powder per Lee's list. but when I weigh it, it only weighs 56.4 +/- maybe a .1

numbers 4 -5 - If I operate the handle as per the book, my charges are way more consistent. I like to refer to it as pouring a charge instead of dropping or throwing.

number 6- There is a rubber wiper. I've taken mine apart and examined it. Lee calls it an elastomer wiper and states that it stops the cutting of the powder granules.

number 7-I only weigh the charges to see how consistent they are. I am not adjusting anything other than the speed at which I pour the charge from the hopper to the metering chamber to the case.

Probably all wrong but it cuts my loading time down at least by half and in the end I see no difference in the way my ammo performs.

[darkker]

1) "I do my own VMD as per the book. And they are always different than the numbers listed example: 4.20 cc should = 58.25 grains weighed of a particular powder per Lee's list. but when I weigh it, it only weighs 56.4 +/- maybe a .1"

2) "If I operate the handle as per the book, my charges are way more consistent."

3) "I've taken mine apart and examined it. Lee calls it an elastomer wiper and states that it stops the cutting of the powder granules."

4) "I only weigh the charges to see how consistent they are. I am not adjusting anything other than the speed at which I pour the charge from the hopper to the metering chamber to the case."

Still gotta get your mind out of this dogmatic "standard" way of thinking...

1) They always WILL be different, because of lot variations. Don't think that "4.20 = 58.25", equals means you saw something in the book and assume you are trying to match it, but you don't have the same lot. Ignore the VMD in the book, and actually do your own. Whether or not it matches isn't important, what is important is that you know your VMD.

2) How consistent?, again if you are judging that by weight, you are missing the point!. Weight is ONLY a reference point to get started in volume. Unless you are using dippers or something to check the Volume you threw, you aren't actually measuring how consistent YOU are; only how consistently the BD appears to be.

3) Just took mine apart again, either it changed or mine is worn off. At any rate, it doesn't matter about cutting kernels. geometry of the surface area is what controls BR, and relatively speaking, cutting kernels doesn't cause a change of significance. Re-read the info in Richards manual about burning rates.

4) That isn't volume, that's weight.... Weight and volume ONLY have a connection to one another, by a REFERENCE. Not a Standard, not a direct conversion, not an absolute; a REFERENCE point. Your powder has a moving bulk density, such a movement in fact that the company that sold it to you won't give you even a hint at how much shift is possible. But you want to WEIGH that moving weight target to judge consistency of a volume?? !!

If you are loading a VOLUME of powder, you can't check consistency of that VOLUME by trying to WEIGH it. They are different systems.
Ever wonder why cooking recipies don't ask for a WEIGHT of flour, they ask for a volume? A cup is a cup is a cup. But every cup of whole wheat flour WEIGHS something different.