Let’s talk about scales. Scales are one of the core components of any metallic reloading setup. Without a good scale you will never obtain the results you need, and with a bad scale, you risk physical injury and catastrophic damage to your firearm. There are two primary types of scales used for metallic reloading; electronic and mechanical. The mechanical scales are sometimes referred to as "balance scales."
Buying an expensive scale does not always result in the accuracy required for our hobby. There are many expensive scales of both varieties that can be purchased and they may not be suitable for metallic reloading. Deciding upon a mechanical scale or an electronic scale is a matter of personal preference and there are pros and cons to each type. Many people swear by the old tried-and-true mechanical scales and there is nothing wrong with that view. I find the mechanical scales to be a little slow for my taste, and frankly I am a technology-oriented person, so I am a fan of electronic scales. With that said, bear in mind that some electronic scales can be affected by fluorescent lights, nearby cellphones or a phenomena known as "wander." Wander is when the reading will change as the charge sits on the pad. Wander can be overcome by purchasing a quality scale and allowing it to warm up prior to use, ensuring that the electronics reach a stable temperature. I generally leave my electronic scale turned on unless I will not be using it for a week or more. I myself have not experienced the effects of fluorescent lights or cellphones but some do report it as an issue. It is also worth noting that either type of scale can be affected by air currents from open windows or air-conditioning vents.
This is an example of a popular mechanical scale: Hornady Balance Beam
This is an example of a popular electronic scale: Gempro 250
Finally a RCBS Chargemaster 1500, which dispenses and measures your charges, is actually available separately from the dispenser if you desire.
You should also consider the scale's precision. Any scale that does not measure in increments of .1 grain or smaller is unsuitable for reloading purposes. Additionally, you need a scale that is designed to have an error no greater than + or - .1 grain. Purchasing a scale that will measure 5.4 grains but may be off as much as .5 grains means that even if the scale says 5.4 it could actually be 5.9 or 4.9 grains in the pan and you will never know. Obviously this is unacceptable. A scale that will actually perform the measurement in a timely manner is also important. Some scales are faster than others and some are just downright painfully slow in measuring.
Any scale you purchase should include calibration weights and a way to zero the scale. The calibration weights are used prior to each session and are to ensure that the scale is still properly calibrated. The weights, which are of known quantities (perhaps 50 grains or 100 grains) are used to ensure that the scale is still measuring correctly and accurately before you start weighing charges.