Have you ever wondered what difference it would make if your patching was just a wee bit thicker but don't want to go back and forth between the range and the fabric store for each experiment?
I have found that by getting a couple of packets of cigarette papers (or any other very thin papers) and inserting 1 layer of paper between ball and patch creates a new combination patch that can effect loading and shot groups. Start with one paper between ball and patch and fire a five shot group from the bench rest.
How did this group compare with the groups fired with your regular patching?
Then try it again with two layers of paper and compare the two groups. It just might be a tighter group. If you could still load with two sheets of the thin paper stock without pounding, it would indicate (to me) that your regular patching is way too thin.
If pounding the short starter wasn't involved, try it again with 3 sheets of the thin paper. How was the group this time? And so on.
If you are fortunate in getting an admirable group. Measure the thickness of the patching plus the same number of the sheets of thin paper stock and you'll have the thickness that is closer to ideal for your rifle.
Get some patching that measures the same thickness of your compound patch and you might run this same experiment again to see if you can further fine tune the patch thickness.
I found that a difference of .0005 made a big difference on my group. I was extremely surprised that such a little difference could have such an effect.
Try it, it might surprise you.