An end effector for use with a surgical fastening instrument is disclosed which comprises a staple cartridge and an anvil. The staple cartridge comprises a cartridge body including a deck and, in addition, fasteners removably stored in the cartridge body, wherein each fastener comprises a base and a leg extending from the base. The anvil comprises a tissue compression surface and forming pockets defined in the tissue compression surface. Each forming pocket comprises a first end configured to receive a staple leg, a second end, a central axis extending between the first end and the second end, a concave turning surface extending between the first end and the second end, and a channel defined in the concave turning surface, wherein the channel is laterally offset from the central axis.
