This may be a silly question, but here goes. I use a GemPro 250 electronic scale for my powder Needs. I always calibrate this device with the included calibration weight, (20gr's unless I'm mistaken) is there any reason that something would be off at say 10.5gr's when my calibrate weight is right on. I have considered getting a secondary electronic scale to verify, but don't know that it is  necessary. I am seriously anal when it comes to reloading, a carryover from my inventory / asset management IT position I'm sure.
Thanks in advance

Ken

I always double check my scales, usually a 17cal 17gr match bullet on lighter charges.

Ken, I've never seen a digital scale sold into the reloading market capable of reweighing the same weight in a 24 hour period and get the same results. Some won't do it in an hour. But to put it all on the table, I haven't used EVERY digital scale out there but in my research I've also found those that are sold for the reloading market are generally over priced cheap crap. If you really want an accurate scale you need to move up to a jewelers digital scale. You can buy a decent one for under $100.00 but make sure it has over weight protection. This protects the scale from having too much weight placed on it which destroys the scales sensitivity. Most will have different weight measurements like grams, pounds, ounces, grains, carats, etc. but make sure grains is on the list. They will also be rated for accuracy. Example would be a scale rated at .001 grains+/-. Research digital jewelry scales if you want accuracy. The crap they peddle off on the gun crowd for WAY too much money is a shame. Here's a good website to start the research on. They carry just about any kind of digital scale made. The one this links to is an Ohaus Scale and probably more scale than you'd ever want or need. It's also $268.00. But there's a lot of info about it that you need to know about when buying any digital scale.
https://www.oldwillknottscales.com/ohaus-scout-sjx-1502n-e.html

Thanks Trapper

Ken

I gotta second trapper6l's experience.  For my money it is pretty hard to beat a beam balance for accuracy and precision.

Me too. I have a Dillon beam scale I bought a long time ago. Most of the time I use my RCBS Chargemaster scale. But if I want to check that one, I weigh the same check weight on the beam scale. They're slower to use, but a long as they're leveled and zeroed correctly, nothing ever goes wrong on a decent beam scale.

Just a little public service announcement for Beam Scales...take care and keep them clean, especially the "V" blocks of the pivot point.  Sweep them often with an artist paint brush to remove any dust or other debris that may find its way there.  The "V blades" of the beam can be wiped with rubbing alcohol to clean.  These steps can keep your beam scale working great for many years to come.

I have been using my RCBS 5-10 beam scale since 1978 and it is still in use today.  I have a cheap digital that I use to find unknown weights faster. 
In closing no matter what scale you use, get to know it and its attributes as some have things like only even numbered 1/10ths, most will drift, can you tare the scale "zero it" with various scale pans.  That come in handy to compare things between two different scales. 

I do use my beam scale along with the GemPro 250, and find I have to recalibrate the GemPro several times over an afternoon. I also find that turning on the scale a few hours in advance helps. Thanks for everyone's input

Ken