Honestly, I would've thought that 2.6 gr of nearly any suitable powder would at least get the bullet out of the barrel.
The ones that actually worked correctly, how did they perform?
If they just sort of lobbed out with no real velocity to speak of, then I would say that 2.6 is too light. If you experienced extreme differences in performance (Bang, BANG, pop) than it's likely charge variation, or perhaps ignition related.
“At the core of liberalism is the spoiled child – miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats.” — P.J. O’Rourke