You need the right cutters. I use some old cutters that look a little rusty and but they have the right heft and sturdiness to them. When angled just so and with a little prying motion, they knock off that die cast tab completely almost every time. Just don't shoot your eye out. If there's a little burr, leave it. It will help the pot stay located.
Incidentally I have had some problems buying tools recently. I just bought some flush cutters that looked very popular and had high ratings but they're really not that great. I was trying to cut some flat nickel wire and the edges would wonk out on me if I didn't hold the wire in the right way. I have old tools lifted form my fathers EE stuff and they're still kickin'. I have some needle nose pliers that are literally from the 1970's and they're solid. A lot of new tools are just garbage. If someone has a recommendation for small flush cutters, please provide a ref.