I'd be interested in how it works well since last I tried the drivers had issues with rolling x and original guncons. Only third party guncons would work correctly though I never tested one of those.
Considering how many of us still use a CRT it's surprising there is no real support for real lightguns.
Since most gun games work using the same technology it wouldn't be hard to interface one with MAME, it's just the software side of things that would need modifying. And of course you'd need a 50/60hz CRT.