Like leaving only guns to my kids when I'm killed, I got an iron will
A will is documentation of where you assets go when you die. Royce Royce is saying his kids inherit nothing but guns and another name for a gun is the Iron.
The other meaning is Royce is incredibly determined.
To help improve the meaning of these lyrics, visit “Merry Go Round” by Royce Da 5'9" Lyrics and leave a comment on the lyrics box