Kind of begs the question as to why these types of flask spouts are sold if they are considered dangerous. The short answer is, because people buy them. :idunno:
Back when I started shooting black powder in the 70's, those bigger spouts were pretty popular, especially among the Civil War guys. The idea of a spark exploding the flask was never considered. But, as the years moved on, stories emerged of sparks in barrels touching off flasks, and ruining people's hands and eyes. I think like any good story, the myths outgrew the actual incidents, but still, if there is any chance of a spark setting off a powder container, why take the chance. I reckon these spouts were made back when it was ok to use them, and are still available on the market.
It took alot of conscience effort on my part to break myself of the habit of dropping powder from my flask directly into the barrel. If I was using an 80 grain measure and wanted to try 90 grains, it was just easier to guess at 10 grains in my spout and dump it in. Now I use a seprate measure every time I dump powder down the bore.
That pre-mesured spout is not a bad idea though. You may find that with practice you can speed up your loading time. Just make sure you transfer the powder to a separte measure. Bill