I have made 'shot' cartridges before, and they are a wee bit faster than loading from an Irish bag....certainly less "steps" and less movement on the shooters part.
I have posted this several times, but there is always a chance someone new will see it, and perhaps improve on it a bit.
I used plain paper brown bags...for a couple of reasons, but mainly because they are 'stout'.
I lay out my paper, measure off the size square I want, and cut it with one of those little round thingys I stole from my wife's sewing basket....be careful they are dangerously sharp and cut in every direction until you get a grasp on how it should be used. This particular one is for a .69 smoothie, and measures roughly 3.5" x4"
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I then I put plain old Elmers's glue on one edge of the paper, and using a dowel of the proper diameter (This is a stick of pipe-dope for Propane gas lines.) I add my cushion wad, and roll it up tight...and remove the dowel.
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This is what your components look like when laid out together.
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I use Anhydrous Pure Lanolin to lube the "cartridge pack" with after it's loaded, and although I have a dipper for my lead, you can use your powder measure to start with.
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The old saying, "Equal shot to equal powder" is still a fine place to start.
As was said, a pre-measured charge in a similar homemade tube serves well for the powder...simply tear off the top, dump the powder, wad-up and push the paper down the bore.
Then..start your "shot cartridge" until only the tag end is out, tear that tag end off and seat a nice tight OS card and you're ready to go.
You can even have "some control" over your pattern by not tearing the tag-end at all just seating it with one, or even two, OS cards on top. I have actually folded and glued down what would normally be the tag-end...and that is very unpredictable.
However, over the years, I have found this method of pattern control a bit iff'y at best, some fairly nice full-choke patterns at 80+ %, and some no larger than half gallon milk box, and shaped very similar.
This, of course, would be a great Turkey Load if one could repeat it, but I have never been able to repeat it, it was always just a fluke.
This may be the challenge you face.
Still yet, IMHO, the very best way to control pattern in a smooth bore is by controlling the height of the shot column...seems to work best for most folks.
I would suggest sticking with tearing the tag-end off the shot cartridge, seating an OS card, and let the barrel do what it does best with this combination. I believe, the pattern is a wee bit tighter with this process as opposed to just loading components...but, I have no proof of this, and perhaps it only seems that way to me.
Uncle Russ...
I forgot to add that many folks advocate the use of "Dime Wrappers" for their shot cartridges, but I have never been fortunate enough to own a bore that was just the right size for a Dime Wrapper, and that is what led me to rolling-my-own so I can get that just right size to easily fit the bore and seat on the powder.....those who can use 'em, and do use 'em, swear by 'em.