I think if you search history here and the LF Forum you will read many suggestions to do 8x10 in the Expert drums eliminating many problems. I have used Rollo Pyro for 4x5 and 8x10 in Expert drums on a CPP-2 since early 2004 with no problems. I have also used Rollo Pyro doing two 7x17 in 2850 drums without problems. When trying three sheets of 7x17 in a 3063 tank I got both the ridges you describe and uneven development. At $7 a sheet, one bad run was enough experimenting there.

John Powers