I think it first depends on if the gun is built around the 40 caliber or originally a 9mm bored out and modded to shoot 40. IME, most 40cal guns are designed around the 180gr round. Shooting something hotter like a 165gr round can definitely stress and break parts more frequently. At one point I broke practically every part on my issued G22 shooting Speer 165 GD, except the barrel. It was sent back to Austria at their request and they came back with….stop shooting the Speer, it was designed to shoot 180gr.