I used a Walker flask with my horse pistols in my bp days. The charge adjustments are graduated in 10gr. increments with the starting ( least amount) being 20gr. Then it adjusts by 10 to a 60gr max. If I remember correctly, you can "fine tune" the charge by screwing the "plunger" in or out and measuring the charge.
The flasks also have a ball magazine but I can't remember how many it will hold. I modified mine ( extended it) to hold 6 conicals. I also decided to add a cap magazine as well. It holds 18 caps.
Here are some pics :
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View attachment 1142121
The above setting is for a 60gr charge.
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This is the plunger that plugs the spout when not in use ( and can be adjusted for depth when spout is closed). You can also see the door for the ball magazine.
Here's mine with the mods I mentioned:
View attachment 1142131
One other useful mod was to make a "wing screw" to replace the tiny screw that allows the charge adjustments.
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Hope this helps with some understanding.
Mike
By the way, here's what charging looks like:
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Plunge to charge:
View attachment 1142142
and there ya go.