Berks, I use to make them before jug choked my barrels, it did make a measurable difference. I used 3"x5" index cards, cut to size. They would make a wrap 2ply thick around a metal dowel, it would end up the diameter I needed for the gauge I was using. I would leave enough material above the end of the dowel that would almost fold to the other side, then fold all the way around, and give the folded mass a few taps with a leather mallet, roll the corners of paper while still on the dowel. They never came undone, even after many trips to the field. I hope I explained well enough, if not feel free to ask. Jug choking makes everything so much easier.
Robby