Hello everyone. I just got a new Rem 870 Express, 18" bbl with the factory 2-shot extension (model 25077). I am having a difficult time with field stripping it. The manual does not cover the models with extension tubes. I called Remington, and the nice gentleman said that the very end of the extension tube is what I need to unscrew. It is on extremely tight and won't budge. The nut (if you want to call it that) at the base of the extension tube, just forward of the fore-end, will loosen but only with tons of torque. I have already scratched this nut trying to get the darn thing off. Can anyone shed some light on this before I go crazy? I have other 870's and it shouldn't be this hard to take it down for cleaning. Thanks in advance for your assistance.