So this is a thing that I'm sure many of have thought would work, but never accomplished. My wife and I just backed this Kickstarter (the 2-gun pack for ~$240 USD). It works on any screen - CRT, LCD, OLED, PDP, even PROJECTION! 5ms tracking/image processing time on top of any obvious screen latency. But dat accuracy... dang!
Right now, the only downside that I can see is that it requires a white border around the game content in order for the camera software to "see" the bounds of the screen. However, that's a small price to pay for ZERO calibration, being able to move around the room/couch, rotate the gun, etc. Seems super versatile and crazy accurate!
https://www.kickstarter.com/projects/sindenlightgun/the-sinden-lightgun/description