I found this thread only because I had to have Google settle this once and for all (as we know Google is all too good at).
I am Cuban and I often naturally assume a Romance pronunciation of words first. So, I rendered Calibre as
kəˈliːbrə (not unlike our French friends would).
My wife just called me a moment ago asking for help with Calibre. Keep in mind, she was the one who always pronounced as intended and first corrected me! Anyway, she said
kəˈliːbrə on the phone! ha!
I have to be honest, I always say Calibre (Caliber) out loud now, but cannot prevent myself from simultaneously saying
kəˈliːbrə in my head.
Thanks for all your hard work, Kovid!