Alan, I did not read it. I don't know where it is.
My magazine well is about 19.5mm in front (.780") and 27mm in back (1.065")
It looks wide enough that I am sure it's not a single stack. It's just that it contours in towards the front faster than the old Lithgow #1 Mk 3 I used to have
(at least I think it does, but as I said before, I am trusting to memory here. I no longer have that rifle, so I can't be sure.
Steve