I have a PPM and I find it to be a very accurate measure. Actually the most accurate I have tried. But you need to learn the secret PPM hand shake 1st.
I am on my 2nd PPM. The 1st one I tossed in the trash because it caused me way to much Angst. One grain variances were not uncommon. Especially with flake powder.
Since I load a whole bunch of Unique. That was a problem.
I had read that the RCBS Uni-Flow was a good measure with flake powders, so I got a used one. Turns out it is a very very good measure with flake powder. Once set up I confirmed a less than a 20th of a grain variance from drop to drop.
I found to my dismay that the UNI-Flow is a dog with extruded powders. Sounds like a coffee grinder when in use its cutting so much.
Since I was broke and in need of a cheap measure. I gave the PPM another try. Figured I could trickle my low volume rifle loads any way.
Once I got it. All the reasons I tossed the other one came back.. But I kept after it.
I took a close look at the Uni-Flow and the PPM to see why it performed so badly with flake powder.
Lo and behold, Just looking at the two measures you can see why.
The problem with flake powder is air space between the kernels from drop to drop.
You take out the air space you take out the errors.
The Uniflow accomplishes this by being nothing more than a funnel feeding the drop tube. All the weight of the column of powder forces it to self pack taking out the air space. As long as its at least 1/2 full you get good drops.
Compare that to the PPM and also the LEE Powder disk measure. They have a small hole that feeds into a small cavity that then feeds the drop. There is no way no matter how much you shine and buff the parts that this will self drop any flake powder with out air space variances. Not going to happen, there is just not enough weight there to pack the powder.
Once you know whats causing the errors you can take that out of the equation. If you ever get a error higher than your set wight your not doing it right.
If you set the measure at a full packed drop. It is imposable to have a high error. You can not get more in than full.
Practice the double tap method:
When you raise the lever on the PPM tap the screw at least twice. Good taps too, no petting allowed.
What your doing is packing the drop tube.
Then when you drop the charge tap it twice more. This forces any stubborn powder to evacuate the tube into the pan.
After I used this technique for a while I found my drops were holding weight.
I tested this over 100 drops and I found with taking into account how the measure works and following proper technique.
I was getting less than a 20th of a grain variance in 100 drops. Plus it works well with stick powder with no cutting.
Not to bad for a $19 collection of plastic.