Amesbury Key blank that fits their locks is thinner than standard keyblanks. Some other brands of blanks will not go into the key way because they are too thick.

Amesbury Weiser Keyblank Thickness: .077" (1.95mm)

ilco Brand Blanks - Brass
Weiser: .081" (2.04mm)
Kwikset: .080" (2.03mm)
Weslock .085" (2.17mm)