Yes, it certainly isn't right. Until I get it off I won't know for sure, thats the challenge right now. I may just mod my current tool to get it off and buy a new one afterwards. Would like to buy the right tool though. Strange that the tool I have is wider and impacts the spider as well as being too wide the other way for the lock ring. Has worked on m952 and other middleburn cranks fine on many occasions.
There are two similar but not quite identical tools, one for XTR, the other I think for ISIS bottom brackets.
The genuine XTR tool has longer dogs on it, possibly also a slightly smaller diameter. It would appear that they are broadly interchangeable...but not quite. It's a bit like freewheel removers.
There is a revealing description:
"Note: The BBT-18 is an updated version of the current BBT-8. The outside diameter of the tool has been changed so it provides a universal fit on all Shimano and ISIS Drive eight-notch cups.+
The BBT-18 has 8 notches with an outside diameter of nominally 43.4mm. The inside-to-inside width is approximately 38mm. Each notch is approximately 3.9mm wide. The hole in the center of the casting is 22.5mm, and will not fit over the 30mm spindles."
That is interesting. Have to say mine looks like the un91 tool as prongs are longer. Perhaps a dedicated spider lock ring tool or the universal bbt18 is the way to go.