I was getting ready to load 13 grains of 2400 on my Dillon 550. My single beam Ohaus scale read 13 grains. As always, I threw 10 charges to confirm the setting on the Dillon. 13 x 10 should be 130 grains. The Ohaus single beam scale indicated only 105 grains. So I weighed each charge at 13 grains and dumped all 10 on the Ohaus single beam scale and again they weighed 105 grains. This is impossible! I weighed a 130 grain .270 bullet and it weighed 130 grains.
I pulled out the RCBS Chargemaster and 10 loads of 13 grains weighed 105. Now the demons are messing with my mind.
So I threw one load from the Dillon and weighed it on the Chargemaster. 10.5 grains.
OK. The error is mine. I looked at the single beam Ohaus scale and instead of setting it to 13 grains I set it to 10.3 grains. Ugh. I have been loading a lot lately due to a stay at home order, and I have loaded for years, 35 tubes of lube in 10 years, and I have used this Ohaus single beam scale since 1978!
Hope you find my bone headed stumper entertaining.