Out of boredom I thought I would rig a sail to see if I remembered how.
I tried to use my Chinook standard ext in a NP X9 mast.
Bugger, it doesnt fit. Only goes couple of cm's before it jams.
The ext fits in every other mast I have so Im curious.
does anyone know if certain brands of masts are smaller ID than others??
Seems strange
Pryde have a habbit of doing that, some of there chinook cup style uni's don't fit other brands either, everyone else has managed to get them the same. Bloody Neil Pryde.
Yes, I guess you'll have to go buy a neil pryde extension. 
Actually my north extension fits 99.9% into my np x3 mast, ever so slightly small when not rigged.
My chinook boom head doesn't seem to fit any mast shim.
For my chinook boom head I trimmed the guides at each end of a fiberspar shim, taking about 5mm off each one. Now the chinook head fits it like a glove.
I had the same sort of problem with a chinook extension once, I removed the plastic top cap from the extension and it slid in no worries. I then wrapped the top with duct tape until it was snug enough to give a nice fit. Worked this way for ages. Of course not such a great idea if you have two masts from different companies.
We have 3 neil pryde masts (2 at 30% which are 430 and 460. Then 1 at 60% i think which is also a 460) and have never had a problem with this. Our masts are a bit older and apparently they have got worse in later years, but we don't even use great uni joint extensions. We just get the generic ones with the single pin in the bottom and extension which goes up into the mast (prolimit, gradz etc) which are plenty fine for us. Not sure if chinook or north make them more difficult or anything like that?
Bubs
EDIT: We also have two fiberspar masts and have had no issue with extensions not fitting (1 is a 400 which is a 370 and 430 together that we made and the other is a 460. Not sure of carbon percentage).
the new x9 racing masts are designed to be used with the np mxt system. they are great extensions but pretty pricey. but instead of buying a new one you could just file down the plastic collar on the extension you have which is what my dad did. he reckons it works fine.
Thanks fella's. I shall try all the advice given.
I love the masts and they work fine with all my other extensions but was a bit surprised that Chinook (being popular world wide) didnt fit.
Will start with removing cap.
