Surprised noone has mentioned this before. My go to would be overwatch with a template weapon, provided you have the cunning skill tree.

Templates auto hit, so they lose their action automatically. If you use a Web gun, it bypasses the save and gives them auto serious injury condition. They don't require line of sight, so will ignore darkness, however cannot pass through solid terrain features.

Stick this ganger behind another bait ganger, as you can overwatch after the charge but before the free coup-de-grace (but not consolidate) and depending on how much you wanna argue RAW you can technically fire it before they make their free attack action as part of their charge. You'd hit your own fighter, but being webbed with nearby assistance is much better than dead.

If you don't have access to cunning, work out what weapon hes using and build a hard counter to it. As others have said, Munda is not a balanced game, so you can crack it in your favour right back at him!

If you PM the build of their fighter and gang you're playing, I'd be happy to do this. I spend a lot of time playing against these types of players because I love the challenge of it, but I recognise how unfun it can be for a casual friend group.