Hi there - here’s an image. I can’t find any reference to it in the user manual re dimensions. I’m starting to think I’m the only person with one at this point! Gun is about 4 years old.
My ge shotgun had a leak and I could not solve it and I was ready to bin it. My pal pulled it apart and a nut further up that secured the gas pipe was loose. I think it’s shagged long term but the symptoms were just as you described