Ho,
You've got the consistancy right on the money, that is the single most important factor to BP loading ( I Think ). I use the method I descriped of weighing to gain this consistancy once i have verified the volume loading. Interesting enough the weight of the same volume charge i use will vary from time to time, thus the reason for weighing each and every charge. Once again before some body gets there panties all in a bunch. This is the was I do it, I am not saying that it is the only way or even the right way just "MY" way. Must not forget those disclaimers in this posting crap.
Ho, i also think you are correct about being able to overlaod a BP case with too much powder. In my humble opinion this is not going to happen unless some fool comes along and uses a case full of primeing powder like 4 fg. As an example when Meacham or Shiloh or any maker builds a rifle they use the same barrel and steele and etc for a 45-110 as they do for a 45-70 thats a 40 grn difference right there.
Gunny