Cheers Mike, Lee, Komatias

The guy I've been watching a lot recently is Stefan Gotteswinter and he likes to use the internal mic. But yes many others use the telescopic gauges and then mic them.

In the work discussion calipers were mentioned as a very cheap way to measure bores (I already have the external mic), but takes some feel/practice. I forgot to mention that above so thanks Mike. Great to hear you worked in the inspection area - that's what I like about this forum, such a wealth of experience to tap into. So I'll most likely get an internal caliper anyway and have a play - not that expensive.

Dial bore gauges look interesting, one to think about.

I'll sleep on it and bit more . . . .