The .40 is a higher pressure round. It is moving a good bit faster than most 45's ever will so the muzzle flip can get a little...snappy. I like a 40 when it comes to steel frame guns. The lighter poly fame pistols usually have a harder recoil. I have one Browning that's a poly pistol chambered in .40 though and I like it a lot. I go back and forth between 40 and 45 a lot and I guess I'm just more used to it. I really don't notice the recoil much anymore.