Making Paper "Cartridges"

[Mr. 16 gauge]

I carry my charges in small, glass vials that I get from work (I'm in the medical profession) and stop them with a small cork. I have a thin buckskin strap that attaches the cork to the vial, so it cannot get lost.
I tried to do the paper thing with birdshot for my trade musket...premeasured charge of shot that I could just dump the whole thing down the barrel (no pouring) and be good to go....the idea was that the set back from the ignition would rupture the paper sack and let loose the shot charge. Unfortunately, it is inconsistant.....sometimes it works, sometimes it almost works, and sometimes it doesn't work at all, and I have a big, gaping, cylinder sized whole in the patterning board.
guess it's back to pouring shot.......