Hey Rick, the chest size of 42" is more like my large, but don't worry the size is just so you don't have excessive strapping you need to start tucking in or cutting off, they still have adjustment room in them. I am the same size as you so it will fit well buddy. The size thing comes into play if some one is smaller or larger to be fair, M and L are very close.
OK, a little update. Also, I just got more metal rings in so all the members who have given sizing will be sewn up by tomorrow. I am waiting for the mounting rectangle rings (at the new size) and they will be ready to ship.
Hey BFUK, if you wouldn't mind, I'd like to go the Medium route. Just did a retape, and I'm BARELY over 40". Plus, the last harness I had was a medium, and there was a substantial amount of webbing left over.
As Gav says, got you covered - and sewn. All sizes given have now been sewn. Once I have the rings that hook onto the pack they will finished and ready to ship. Still some members listed as interested to confirm sizing.