A surgical stapling instrument includes an anvil and a stapling head assembly. The anvil defines staple forming pockets. The stapling head assembly includes a body, a coupling member, a firing assembly, and a staple deck. The coupling member is configured to actuate relative to the body to thereby acuate the anvil relative to the body. The firing assembly is configured to drive staples against the staple forming pockets of the anvil. The staple deck is defined by an outer arched perimeter and an inner arched perimeter fixed to the body. The staple deck defines staple openings. At least one non-tangential staple opening in the of staple openings extends along a longitudinal axis in a non-tangential relationship with a closest tangent line of the inner arched perimeter or the outer arched perimeter.