Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
nitty-gritty [ˈnɪtɪˈgrɪtɪ] n (inf)
to get down to the nitty-grittyпереходи́ть*(перейти́*perf) к су́ти де́ла
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.