My gun seems to shoot the same clean or dirty although I do clean after every 5 shots when sighting in. I' m with Bigcountry on the oil. I always run a patch wet with rubbing alcohol and then a few dry patches before I shoot if I had previously oiled the barrel. With an oiled barrel my rifle will generally put the first shot high and to the left. I can' t explain why but I have checked it several times and it' s always the same.