How hydroscopic do you find 777 pellets to be?

I shot a bunch yesterday from my speedloaders (loaded last year) to get rid of them and litterly was all over the place. Same thing happened last year. Broke out the ones I sealed in a plastic bag in the box, and back to 2MOA accuracy.

I know any blackpowder or pyrodex product, can collect moisture. Just didn't think 777 pellets would. Velocity was also all over. After two years, same thing, I think they are prone to moiture issues.