I'm getting back into the swing of some lightgun projects (I had been on and off working on the Topguncon project and it's flasher for some time) so I had to check out sonik-br's driver with psakhis's daemon.
I'm getting some really good results with it so far. A name-brand guncon2 is working without rolling-x. The flasher works well, and even without driver calibration the shots are placing pretty consistently for me. This is an exciting time to be tinkering with crt guns!

It also pairs well with the modified pcsx2 that pcnimdock has just posted! I recorded a quick demo on Time Crisis 2. I was able to bind the sdl joystick axes to the left and right axes in the Guncon controller config, though I did have to go and edit the pcsx.ini afterwards as it was pretty sensitive and picking up multiple axes at once. My guncon config section looks like this:
[USB1]
Type = guncon2
guncon2_Recalibrate = Keyboard/Z
guncon2_Select = SDL-2/X
guncon2_Start = SDL-2/B
guncon2_C = SDL-2/DPadUp
guncon2_use_gamepad = true
guncon2_custom_config = false
guncon2_A = SDL-2/Y
guncon2_AimX_L = SDL-2/-LeftX
guncon2_AimX_R = SDL-2/+LeftX
guncon2_AimY_D = SDL-2/+LeftY
guncon2_screen_height = 480
guncon2_center_y = 240
guncon2_AimY_U = SDL-2/-LeftY
guncon2_TriggerDeadzone = 0
guncon2_ShootOffscreen = Keyboard/X
guncon2_Trigger = SDL-2/A
Here's a demo - ignore the first couple shots being a bit off - had to adjust my hands in recording. In play it was quite snappy. My guncon psakhis daemon settings were:
run -f=3 -d=0
In my case I was able to use zero input delay after the flash (d=0) but I feel like other games/emulators you need this. From my own experimentation with Topguncon this was needed for some games if the flash was happening 'after' the input.
https://drive.google.com/file/d/1Kd42jOZTnRInbAxcSnXc10TkSy6uqg1H/view