We tried it zeroing on a case then sorting by weight difference and by zeroing the scale and separating by actual weight. We compared between scales and found they often differed by .2 and once in a while .3 grains.My brothers reloading room is draft free with a very solid and level bench.

After contacting Lyman, RCBS and Ohaus I have gathered the following information:
Most of these scales use strain gauge technology. . Learn more on strain gauges at http://www.sensorland.com/HowPage002.html

The strain gauge can give you good weighing results for static loads, but can drift much more due to temperature variations which may occur by just by using the scale. Especially those with the feed motor (like the DPS 1200) which will generate heat just from being used. Zero often, and calibrate when suggested by the system. Any voltage fluctuation may confuse the electronics into thinking the load has changed.

These scales are VERY sensitive and will detect any movement which could cause the strain gauge to flex at all under it’s load (including the empty pan). Light drafts can be caused by the movement of your hand while loading the scale and will affect the reading, but should stabilize once the ‘breeze’ subsides. Test it – it’s cool!

Any vibration of the scale will affect the reading if it causes the scale to move at all. Another fun test.

AC Line noise will affect the scales, a line conditioner is an excellent investment.
Fluorescent lights are not a problem unless they are close to the scale, in the 2 to 3′ range.
Cell phones can cause interference with electronics, all recommend that they be turned off if near the scale (10ft). My scales went crazy whenever my cell was in use (dialing – talking – etc.) and did ‘wander’ more when it was just in my pocket turned on. We had to move it 10 ft away before it stopped bothering the scales.

Both RCBS and Lyman offered to evaluate the scales for me, I paid shipping, which I will do, and am grateful for since they are not brand new. Both then replied that the scales were out of warranty and they only offered to sell me new scales – I took the offer and got a new DPS 1200.

You’ll see get better performance, linearity and repeatability with an electromagnetic weigh sensor which cost a whole lot more, and takes us back to the “Does it really make a difference?”

I have received a lot of feedback asking “What am I thinking and why worry about it so much?”. Well the answers are simple in my mind. The pursuit of perfection is why I got into the hobby of shooting, smithing and reloading. It’s fun to be able to make one hole. When I screw up and miss blow a group, I like to be able to prove to myself that the variation was the shooter (me) and not the other variables. For me this is fun.

The other concern I have and wanted to understand is regarding loading pistol rounds where a tenth of a grain is much more of an issue than with my 25-06. My brother and I load 17 Mach IV (17 Fireball) and 460 Rowland cartridges which are by nature fairly hot and sensitive to load variation. A couple of tenths of a grain will make a significant difference. (If you haven’t shot a 460 Rowland in a 1911, you have to try it, Clark makes great barrels and they shoot great. http://www.clarkcustomguns.com/rowland.htm )

I have purchased an Acclab VIC 123 which reads to .01 grains and have found it to be extremely accurate, precise and reliable. While it reads to 2 decimal points (.01 gr) I can not use that digit, since the scale does have some measurement error as an electronic / mechanical device. But I can ALWAYS rely on the tenths (.1gr) reading with confidence. .1grain is as precise as I need to be for any of my activities and this ability has allowed me to significantly shrink groups. After trying different RCBS, Ohaus and Lyman DPS scales, which all read to .1grain, NONE of them were reliable for measuring or sorting to closer than 1 grain.

Keep them tips coming!