I've owned my RCBS Uniflow since the very early seventies, when I first began reloading in earnest. It's always thrown powders pretty much "dead on" plus or minus perhaps a tenth.......very reliable.
Yesterday I was setting up to throw 16 grain charges of 2400 for a military cartridge. As is my habit, I always throw the first 3 -5 charges in my scale first, this being my minimum to verify everything's all set.
Suddenly the charges began weighing 15.6 to 16.2......? Repeated weighing got 16 grains (dead on) a number of times, then a repeat of the error. Note: The scale (an RCBS 505) is level and checks out.
I finally grabbed a box full of spare Uniflow parts and swapped out the powder drum for a brand new one. This time I got 16 grains, and then suddenly a repeat of the error. I adjusted it several times and got the same results.
I'm stumped. Is it possible that the error has been there all these years and I just never noticed before? Could it be the powder? I had this happen years ago and it turned out that I left the "small" funnel in the measure, which caused the stick type powder to bridge. Not the case here though.....large funnel is in place and 2400 usually meters beautifully. Any suggestions gratefully accepted!