Shackler's Revenge by Guns N' Roses - Full Band FC

I was always under the impression that this song was about school shootings, with the first half of the song in the voice of the shooter, while the second half is Axl's own feelings. This is apparently not the case. But that begs the question: who is Shackler and why do they want revenge? Were they upset about the album taking 10 years to make? Were they upset how stupid this solo is? Were they upset about how atrocious this cal is? I'd understand completely if it was the last one.
Nice job to everyone though! Especially Surly - he's a good guitarist and all, but is he has good as this guy???: tinyurl.com/4P...
Guitar- Surly
Bass- Jo
Drums- Brian
Vox- Elder