I've got a slightly older Montefeltro Super 90 12ga (not an H&K import though) and cannot figure out how to remove the damn plug. I pull off the forward cap to access the plug, and it slides almost all the way out but seems to be captured on the inside of the mag tube. I can't figure out how to get into the damn mag tube without actually removing the mag tube. Some Googling shows other Montefeltros where the plug just slides out the front. Mine acts more like my SBEII which has the stupid snap ring on the inside, and you have to partly disassemble the mag tube to access it. But on the Montefeltro, there are no flats on the mag tube end that would allow me to remove it.
I swear I'm not a moron.
I don't really have any reason to remove the plug, but I was going through it this evening to replace all the springs, and couldn't figure it out. I've never tried removing it, but not knowing how to is driving me nuts.