I shoot a 58 Remmy in .44 & my loading process is to take the measured charge from the metering spout in the flask, dump it into a brass "transfer case" (a .44 Mag shell casing) & then drop that into the chamber, top off with wad & ball then ram. I do this to avoid the possibility of an in-flask KABOOM!
i use a flask and a 25 0r 30gr spout and pour the charge into the chambers using the flask and spout directly. If I'm working up a load or shootin' a rifle only then do I use a measurer.
you can use anycontainer to fill your chambers, accuracy depends on repeatability and the same charge in each chamber everytime ...the numbers are basically referance points.
That's how I see it anyway... :O)