Found a reasonable used North mast which seems to be 460 cm and 15 % carbon.
It looks to be in good shape.
I am still looking for a 460.
As a heavyweight in a lite wind region, my sails are 7.0 and larger and go on 490 and 520 masts.
Luckily my 7-oh still fits on a 490, but one day, I hope to use more modern sails.
As such, I imagine 30 % would still be the starting point ??

my current masts are 75 % and 100 % - as marked.

as you go down in sail size i have heard one can get away with less carbon.
and obviously many are using RDM in the smaller sizes now as well.

as usual i am just trying to save some money, but the more i write here, i guess a North 460 15 % SRS is out of the question ??

thx in advance

Hmmm 15% carbon would be a pretty old mast.
Likely to be very very wrong for modern sails regardless of how you tune it.
Just to be sure though, what markings are on it?

I'm not sure I agree with that, I have a really old low % carbon mast that works really well with my 2010 Koncept.
You're looking at this mast with regard to using it for a sail you don't have yet? I'd get the sail first and then buy a mast so you can rig them together and see if the mast bend suits the sail.