Lee 9 said:
I reload for rifle and pistol all by weight, but when I tried it with Blackhorn I got a shock, the weight of Blackhorn varies from lot to lot but it still shoots the same by volume. The manufacturer controls energy to volume rather than energy to weight is what I suspect.
Exactly! It's always the same volume.
If you buy your powder one bottle at a time, from year to year. You are far better off measuring by Volume.
If you buy powder by the case, or 5# jug and can keep it in a climate controlled environment where no humidity can get to it, you might get by by weighing it if it is the same lot#. If it is not stored properly, or you buy a new jug the next year with a different lot#, it can actually weigh more the next year, and you will have less volume of powder in your pan on the scale. Less volume = less velocity!
I learned back in 2008, to use a volume measure for measuring Blackhorn 209. Just make sure you do it the same way every time, ie., tapping the same number of times, and cut off the top.
Weighing and storing in tubes from the same container, will give you the same results, until you have to open a new bottle, jug, or lot#. Then all bets are off.
It's worse with all the other Black Powder Subs, because the granules get smaller (fines) as you use powder in the same jug. That messes with both the weight and volume as granule size changes.
One way to check from lot# to lot#, is to Volume measure out 10 loads of your old bottle, then weigh each one. Then Volume measure out 10 loads from the new bottle/lot#, then weigh each one. Put them each back in the tubes.
Now weigh out three of your preferred charges from the old and the new bottles, Mark them as such, and shoot them with your favorite bullet through the chronograph. Then take 3 of each if your volume measure charges and do the same. Record your velocities, and compare.
It probably won't be enough to cost you a deer out to 100 yards, but it might be the difference of a 10 or an X in a shootin' match.
I had a guy PM me on another site about this very same phenomenon. He measured his loads by WEIGHT, and was getting as much as 8" difference (lower) in POI on his year old powder from this year to last at 200 yards with the same rifle and a 100 yards zero. His powder was from the bottle that was opened the previous year.
He had 2 more unopened bottles with the same lot #, or so he thought. If you buy your powder from a retailer, give the bottles a squeeze. If they leak air, don't buy that bottle. People open the bottles and break the seals, or the caps can loosen during shipping, and bottles in the cases can get squeezed in the pallets during handling. Well one if his bottles passed, and one failed the squeeze test. He has a precision scale that he could weigh the complete comments of each container. The contents of container that was sealed tight weighed exactly 10 ounces. The contents of the container that slightly leaked, failing the squeeze test weighed exactly 10.7 ounces. Now I understand this was not a scientific test by any stretch, but it gave him something to think about while searching for a good Volume measure.
Awaiting his results of Volume to Weight differences from his further testing. Also waiting to see if his POI from his tightly sealed container with his 100 yards zero, comes back up to his POI from the previous year.
Like said earlier, it's always the same volume. Weight to Volume, maybe not so much!