I have the samecleaning issuewith my Omega. I use a brass .22 brush and windex. It is a pain to get to and itdoes leavea stain. If you remove the stock, its a little easier to get to. I have gone through several pounds of BP, subs, pellets with my Omega and I guess I got used to the ring/stain. I have had no misfires or problems with it sealing all the way to protect the 209 primer.