"Blackened" has perhaps the most changing time signatures of any Metallica song. The intro is in 4/4, then 3/4, 4/4 again, and then followed by a 5/4 measure, leading into the 7/4 riff. Then, the verse is in 6/4, going into the 7/4 riff again, then a 2/4 measure leading into the chorus, which is in 4/4. The 7/4 riff kicks in again, then the 6/4 verse, another 7/4 riff, and another 2/4 measure leading into the 2nd 4/4 chorus. Then the slow bridge starts with a 7/4 measure, then 4/4 for the rest until the dual-guitar build-up section, in which every other measure is 4/4, and the other measures alternate 2/4 and 3/4, in that order, but starting with a 4/4 measure. Some find it easier to alternate counting 6/4 and 7/4 measures, or even counting one pattern as a whole: a 13/4 measure repeating over and over until the slow solo, which is entirely in 4/4. Then there is a short 4/4 break, ending with a 2/4 measure that leads into the fast solo, which is entirely 4/4 except one measure before the last part of the solo that's in 5/8. Then the riff starts again, in 7/4. Then one final verse in 6/4, then a 2/4 measure leading into the final chorus, which is in 4/4. The last chorus repeats itself, with different words. This repeat is tied to the previous chorus by a 5/4 measure. Finally, the outro is in 7/4. It is somewhat difficult for inexperienced musicians to count the beat properly during the riff, because of the odd time signature and the accented notes for the melody, as well as the snare, are played on the up-beat.
