For an example of a proper tight weave for use as a patch for your PRBs, go to a fabric store and look at pillow ticking. It is a pretty standard material to use for patching. Also look at such fabrics as pocket drill and denim. My personal favorite is pocket drill. It mics at around .015 to .018. When I buy fabric for patches, I take my clean micrometer and measure the thickness of the fabric before buying it. I know what my rifle likes and I don't buy any fabric that doesn't measure .018. When I find it, I will buy several yards at one time. That way I have a supply of patches that won't vary. When I get my fabric home, the first thing I do is get out the sewing machine and run a row of stitching along the cut edges to prevent unraveling. Then I wash my fabric with just detergent and no fabric softener. Softener effects the absorbancy of the fabric. I run it through the dryer (you can line dry it if you want) and then I run an iron over it to remove the wrinkles. This is not absolutely necessary but it makes the fabric nicer for cutting patches. At this point, you are ready to make patches. BTW, if you don't run the stitching along the cut edges, they will unravel and you will end up with a very tangled mess when it comes out of the washer and you will have lots of threads to pick out of the washing machine. Of course, if you don't have a sewing machine or choose not to bother with it, you just learn to deal with tangled fabric in which case, scissors will be your friend.