well I did a small bit of filing on the pin and got the 10mm collet to slide in nicely, the 12 is a little tighter but ok. unfortunately the 16mm and 6mm are very tight, they will go in, but require more force then I like.
measuring the collet diameter im getting 24.11mm on the two good ones and 24.12mm on the two that don't fit well. have tried spinning them up in the lathe and polishing the collet with some light emery, but not made much difference.
looks like they are about 1 thou oversize.
my cutters also turned up yesterday, . at my parents. . so wont be getting my hands on those for a while