balance beam scale issue

[jlopez]

I have both the RCBS 505 and the Hornady model M balance scales. I have been utilizing the RCBS scale for approximately 10k rounds. I ended up with the the Hornady scale in an estate purchase of reloading equipment. I like the hornaday scale because the numbers are easier to read the tray does not build up any static electricity so when dumping a charge i do not have to keep tapping it. However when comparing this scale against the RCBS with some Clays powder for a 45 acp load of 3.8 grains the hornady reads 2/10ths of a grain lower (ie 3.6). I transfer the powder load from one tray to the next making sure all the powder transfers. I planned on switching to the hornady scale because I like just a little better and planned on selling the RCBS but now this has brought doubts into my mind of which one is actually correct of if both are mis-calibrated. With out having to buy a check weight system is there any other way to validate which one is correct. The hornady appears to have an adjustment via the nuts on one end of the balance beam however the RCBS does not appear to have any adjustment. I would not want to sell either of these until i have the peace of mind of them being calibrated.

Thank you in advance,
Juan