I notice that the Key is inconsistent, sometimes marking the u in pugna/pugnare/oppugnavit, etc, as long, sometimes as short. IT'S SHORT.
But note that the SYLLABLE containing the short u vowel (pugn-) would be considered long in reading (especially important in reading poetry). Check D'Ooge's paragraphs 8 and 13.
If the Key and D'Ooge differ, trust D'Ooge.
Also, to get a feeling for 'double-sounded' consonant clusters, listen to the TTs and LLs in Lorenzetti, Botticelli, Giotto, etc, in this Italian snippet:http://www.youtube.com/watch?v=H-R6m_8Q ... re=related