Powder Scales, Measures, Tricklers, and Dispensers
One of the most critical aspects of reloading is ensuring that your powder charge is correct. There are 7000 grains per pound. So, the weights are quite small and must be accurate. A light pistol round might require a handful of grains of powder while a heavy rifle round might requires 60, 70 or more grains of powder. Accidentally double a light charge, and you might destroy your firearm ... or yourself.
Different vendors make powders with different burn rates. While we won't get into specific powders, it's important to use the exact powder that a particular cartridge recipe calls for. This chart shows the burn rates of various powders across different vendors.

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A typical powder scale which is the type I used 40 years ago is the balance beam type. They are accurate and relatively inexpensive, but--in my opinion--a pain to use.

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A digital scale is easier to use and reads out the exact weight. Most can and should be calibrated as they can be affected by environmental differences such as temperature. But wait ... don't run out and buy once just yet.

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Individual powders come in different grain (not to be confused with the weight measure) shapes. They can all be weighed. Some have more difficulty in being consistently "thrown" by a powder measure.

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A powder measure "throws" charges of powder by volume not weight. It is adjusted using a scale until a consistent weight is thrown with each turn of the handle. Note that your operation of a powder measure must be consistent to result in consistent throws. These are great when loading larger quantities of practice or fun ammo which is not intended for critical use such as benchrest rifle competition and long-range hunting.
Most progressive presses, which are obviously intended for volume production, utilize a powder measure.

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A trickler, as the name implies, can be used to trickle tiny amounts of power, almost down to the powder grain (again by powder shape, not the weight). The trickler is used by slowly rotating the handle/dial which has its powder mouth or opening over a scale until the desired weight is achieved.
Some people use a powder measure to specifically throw a lower than desired charge, which may vary due to the inaccuracy of the volume measurement, then use a trickler to bring to charge up to an exact weight.

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I avoided getting a digital powder dispenser because they're just damn expensive, maybe $250 to over $500. However, I finally did when an RCBS ChargeMaster Lite went on sale. Love it! It accurately dispenses power to the tenth of a grain, though takes a little while (maybe ten seconds). But I can usually have it dispensing the next powder charge while filling a case with the just-dispensed charge.
These are especially useful when testing new loads and creating a "ladder", that is, a series of cartridges with successively greater charges ranging from minimum to maximum. (BTW, for ladders I mark each cartridge case with the actual load using an Ultra Fine Point Sharpie. The marking stays on well enough while I check for signs of pressure, but comes on during the next wet tumbling.))

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I've found two of these Lyman Powder Pals to speed up my powder charging. I dispense into one while emptying the other into a case, then swap. Note that the weights of these are likely to be different, so I attached aluminum tape to the lighter one to make the two weigh the same.

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