Patton was over-egging the pudding when he said that. The vast majority of casualties where inflicted by crew-served weapons, artillery and air-power not personal infantry weapons. During the Franco-Prussian war the French Chassepot rifle was by far a better rifle in every respect than the German Needle Gun, but the French still lost because the Prussians had a comparable superiority to the French in artillery, which by that point was a far more important factor in winning battles.
Also consider that the Lee-Enfield was a considerably better battle rifle to the German Mauser K98 (more so than any appreciable difference between the Enfield and the Garrand, the latter of which also had its disadvantages compared to the former) and yet it took a lot more than a superior rifle before we were able to start kicking German ass...