Load from a calibrated measure.
Be Safe !!!
Reading between the lines, it looks like you are loading directly from the flask but I could be wrong. There is a safety rule out there that warns us about doing so. In all honesty, there are times when many of "us" do just that. I have done it but not as a rule and I won't teach it. Now then BP and it's replacements are very forgiving and being a few grains off will have little or no effect on consistent shooting. I really would not give it much thought. .....I bought a CVA brass powder flask with a 30 gr tube, the problem is it only dispenses 27 to 28 grains not the 30 it is supposed to. Is it defective or this just the way they are, not real accurate ?
Be Safe !!!