[Major Tom]

My DWM pistol has the hold open lever. One magazine, a Triple K brand works flawlessly. The other magazine, an older replacement type does not hold open the toggle. Visually I can see little difference except one measurement. At the rear of the magazine follwer there is a pronounced lip. On the Triple K the lip is .023 high; on the other it is only .013 high. Would this make the difference? Just what part of the magazine trips the hold open lever? Any help appreciated. And, thank you