There are two main types designed for loading shells. The basic balance beam scale is a bargain and is quite accurate as long as you find a place to put it and don't move it around on your bench. Why? Moving a balance beam can altar the reading to be undesirable moving it from one location to another because basic construction of benches/tables/desks simply are very rare to be dead level or square. So, using one should require you to find a spot you like and leave it there or mark the spot so you can use the same place. Even then, you should adjust the balance beam to read dead zero before using it to weigh powder charges.
The second type is the digital scale that is electronic, usually powered by batteries or a low voltage convertor. These are more easy to keep zeroed since there is no balance beam measuring device. The digitals are easy to zero or test by checking without anything on the plate for a zero or with a testing weight that comes with the scale, or with a rifle or pistol bullet of a known weight. The cost is considerably more than the balance beam scales. Both types are sensitive to breezes, even just walking by the device or breathing close enough to disturb the process. Closed windows and doors are recommended and avoid the furnace/air vents or fans. I'll leave which ones to check on to others but I have both a balance beam and a digital from Dillon, no doubt made by some other manufacturer, in Arizona and find both reliable......breakemall