Surgical stapling system comprising a grooved forming pocket

An end effector for use with a surgical fastening instrument, comprising:

• a staple cartridge, comprising:
• a cartridge body including a deck;
• and
• fasteners removably stored in said cartridge body, wherein each said fastener comprises a base and a leg extending from said base;
• an anvil, comprising
• a tissue compression surface;
• forming pockets defined in said tissue compression surface, wherein each said forming pocket comprises:
• a first end configured to receive a said leg;
• a second end;
• a central axis extending between said first end and said second end;
• a concave turning surface extending between said first end and said second end;
• and
• a channel defined in said concave turning surface, wherein said channel is laterally offset from said central axis.

An anvil of a surgical fastening instrument, comprising:

• a tissue compression surface;
• and
• forming pockets defined in said tissue compression surface, wherein each said forming pocket comprises:
• a first end configured to receive a said leg;
• a second end;
• a central axis extending between said first end and said second end;
• a concave turning surface extending between said first end and said second end;
• and
• a channel defined in said concave turning surface, wherein said channel is laterally offset from said central axis.