My .177 Marauder Field and Target has been in a funk for the last year or so. Velocity used to be pretty consistent, usually within 5 fps between shots; that has increased to 15 or more. Shot groups have become inconsistent as well. I suspected it might be the regulator so I replaced the Crosman one with a Huma with really no improvement. I have cleaned and polished the barrel, changed the barrel o-ring, changed the air stripper o-ring (shroud was loose over air stripper), tightened and loosened the shroud with no improvement. I also changed scopes with no improvement. I did notice that after I cleaned the hammer and tube that the hammer became difficult to cock. There is wear (shiny areas) on the top front of the hammer and the bottom rear. I lubed the hammer with a light coating of moly paste and it got much easier to cock but was still inconsistent. I've got over 16000 shots with the rifle so could wear be a factor? Thanks for any advice.