I use Track's Flask-PP-3. Says it throws about 3 grains of 4F powder. I usually just give it a quick push against the pan, which is very little powder. So today I weighed that. The amount is so little that I did five pushes in my powder scale pan and averaged them. The average was about .6 to .8 grain of 4F, which works fine for me. If I have a flash in the pan, I pick the vent to put a hole in the powder column and then it goes. But if the valve spring is pushed and held, more powder comes out. I discovered that if I held the valve down to the count of five, I got a lot of powder out of it, about three grains. What happens there is that the spring loaded hole allows powder to fill up the whole push spout, and lifting the valve shuts the hole off. If I have trouble with flashes in the pan (as with my flint hooked breech plug), a sure cure was to tip the priming powder into the flash hole and reprime the pan. If I wanted to be certain of a flinter going off, I'd tip the flash powder (4F) into the flash hole. This is based on hundreds of shots.