Unfortunately the F&D moderator for my .223 cannot be dismantled. The one for my .308 does unscrew however.I have seen the exact same thing happening at the range. And it was definitely the oil in the mod. It had just been sprayed the night before.
The reason I now also have a F&D mod is that you can open it easily and scrub or wash the crud off on the inside. I am hesitant to spray any oil in it as I am certain that this will increase carbon buildup, burning temperature and ultimately material fatigue. After all, oil will burn and leave residue.
The first thing I did to the new mod was to open it and remove any grease from the inside. Interestingly enough there were lumps of grease on exactly those edges that show signs of deterioration on some of the pictures on this thread.
When I bought them I was told that the F&D did not advise taking any of them apart.





