No, it won't work. The punch is too big to enter the 20 cal. case. You will find this sort of issue a lot with the 20 cal. Most "universal" stuff seems to cover from 22 to 45 cal. Not 20 cal. Example, powder funnels. I did find an RCBS 17 cal. funnel that works fine with the 20 cal., but 2 different universal powder funnels would not work. One was Lee, the other was an antique. Both sold as "universal".