Good advice, for all powders, Steve. Some powders vary more, lot to lot than others.

I do not know about other Vihtavouri powders, but N120 is susceptible to quite considerable burn-rate changes, lot to lot. This is especially noticeable in very small case rounds, like the .17AH and .17HH. Having variations of up to .6 grains in this tiny case, means considerable actual difference, lot to lot. Only having a capacity of 12 to 14gr. makes a .6gr. modification a huge difference, yet it is a very popular powder for those tiny rounds. In my own testing, AA1680 is much more stable, lot to lot, which is slower than the old WW680 - not the same at all, even thought the numbers are similar.

Some years back, Hodgdon purchased from Olin, the last 3 or 4 tons of WW680 produced, then re-canned and labeled it H116.
It was a really GREAT powder in some small cases and especially for producing big velocity at .44 mag pressures in .45 Colt lever guns 200fps faster than WW296/H110 could produce at the same pressures. WW680 was also a super powder in the .17 AH and .17AB(my most accurate loads, in fact in the .17AB).