http://www.truglo.com/content/products/firearm/muzzleloader/muzzle_brite.asp
If your not finding any patches, I am guessing that they are being blow apart. It is no wonder the accuracy is starting to suffer at longer distances. Try some corn meal. 20 grains is plenty. Cream of Wheats can also be used. Although you might become labeled a cereal killer...
Another thing you can do is go to a hardware or tool store and get a cheap 1/2 inch hollow hole punch and some 100% wool felt construction grade. Punch out a bunch of bore buttons. Smear a little more butter on them and use them between the patch and the powder. It will protect the patch and help keep the barrel cleaner.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3838