Walther originally had the trigger bar ears properly designed. Then they began to stamp the trigger bar out of plate steel. The stamping process leaves the bottom edge sharp. Unfortunately, when the trigger bar was formed into shape the sharp edge of the ears was on the up side which is where the rearward moving slide impacts the trigger bar to disengage it from the sear after each shot. These sharp steel ears would eat into the much softer zinc slide. Walther has made some progress in recent years of reducing this by adding an additional stamping of the top of the ears which rounds the sharp edge off a bit. My QD was acceptable. But, I re-profiled the ears anyway. I'll put up some pictures to illustrate as soon as I remember my imgur password. Happens to old peeps.....a lot. 1917
Some years ago this is what a typical trigger bar ear would look like. That top, front edge is the only part that the slide engages and that sharp edge from the stamping process would chew on the knockdown ramps pretty quickly. This is what my mod was about, getting rid of that sharp edge. Later I would determine that if the lever was flipped upside down, and the ears sanded off a bit on some emery paper that the resulting slant would exactly match the slant of the knock down ramp under the slide. This all but eliminates any ear damage to the slide.
Above is a picture of the underside of my slide on a target P22. 2,000 rounds and no cleaning or lubing. Will do a thread one day on it. What is of note in my opinion is the impact area where the ears are hit by the slide. This slide has appx. 12,000 cycles on it. Compare it to yours if you will. My ear re-profiling all but eliminates any deformation of the slide ramps. The light impact areas you see above are simply where the ears have burnished off the spent powder and smoke marks. Walther had this right in the beginning....then dropped it.
This is what two minutes of work makes the ears look like. No sharp edge, the front slope on the ear matches the slope of the ramps on the slide. This is from turning the trigger bar upside down, front of the arms on some glass, ears resting on the edge of some 360 grit emery, slide the ears back and forth until the sharp edge is gone, then rub the ears back and forth front to rear on some 600 grit and this is what you will get. Pretty easy but customer service isn't always happy with home smithin'. You really don't need to even go to this much effort...just get rid of the sharp edge if your trigger bar has them. Or let them chew on the slide and Walther can sort it out....lifetime warranty.
Above is a photo of what the ears can do to the knock down ramps under the slide....and this was with some ears that had been rounded a bit. If you look at the earlier picture you can see that the slanted back ears really minimize this swaging of the zinc as compared to just rounding the ear off a slight amt. I don't remember which slide that was but it probably had 15K or 25K cycles on it.