Some do, some don’t. Some never will, some develop it later. With about 100 GLOCK .40’s in service in my department, many with WML’s, I just grew weary of trying to figure which ones will, which ones won’t and which ones are gonna start malfunctioning with WML’s. And I saw a lot of it too. Sucks, because I love the .40, but I love the GLOCK too. I just don’t love GLOCK .40’s with WML’s. Without WML’s they are stellar performers. We had our same Gen 2’ GLOCK.40’s in service for 18 years and couldn’t tear ‘em up. It wasn’t til we all upgraded to Gen 4’s that we noticed the WML issue. The Gen 2’s had no rail, so no issue ! I know this hurts feelings but it is what it is. I wish it wasn’t. Even so, I’ll never get rid of my G23’s and G27. Just won’t put lights on ‘em.