Got it. But that doesn’t answer the question of what a metal shank is... In prison, it means a self-made knife, for killing other prisoners. What definition is this article proceeding from? Why didn’t they use a different, less evocative term, other than to paint this whole enterprise as extremist?
/johnny
A shank is:
1. The narrow part of the sole of a shoe under the instep.
2. A piece of material, such as metal, that is used to reinforce or shape this part of a shoe.
Not having any other ready sources of metal, prisoners would remove this part of the shoe and sharpen an edge or point on it.
Shank is the term used when a metal strip is put into the soles of boots to reinforce it also. Think the use here is closer to that.