I did a swap and ended up with a 5.5" 625 that was "factory" Mag-Na-Ported. I thought, a 625?? A 629 maybe.... Well to be honest, I haven't fired it yet so I can't report on the recoil reduction - if any. I too always wondered about the real effect on recoil from porting. I know an expert EDM man in Clarkdale, AZ, Tom Aston, who developed a system similar to the Magnaport. He swears by porting and is one of the best gunsmiths (and highly skilled shooter) I've ever met. He built my Colt 70 Series for action pistol shooting. Best shooting pistol I've ever owned. So, I guess I can't say one way or 't'other. If it helps on a .44 Mag, I say great. Not sure why S&W offered it on a 5.5" .45ACP revolver.... H.