As with pretty much any weapon script mod, the way to undo it is unfortunately to restart L4D2. The game tends to stick with whatever guns were in the first game you played after starting it up, rather than loading them fresh every time. This can produce some weird hybrid results.

Yes, well, I have restarted my game several times since then. Every time- slug spas that doesn't crown the witch. G3's are also broken- with the camera angle and FOV distorting, no visible viewmodel and arms becoming textureless.

Scratch that. G3's have somehow fixed themselves.

You need to find a way to restore the original animations. I have no way of figuring out and this is really getting on my nerves.

go to add ons and delete the checked box for this mod

Host the server and invite friends who have the same mods in use and it will. If you host the server and set sv_consistency 0 on it, others can join but they'll get some flicker on the ammo display and they'll see the normal reticle not the slug reticle. They can still use it, aiming with the centre dot, and it'll work for them, but they'll find it odd.

You mean the laser sight, laser designator, gyro-stabiliser, guided bullet, muzzle brake and recoil compensator package? Yes, it's overpowered.

The shotguns in these four mods are all down to 0.1 degree scatter for their single high-powered "pellet" per shot, though, so that group size isn't just down to the laser. At 100m, that's a 1.75m group. Maybe you wouldn't hit the tank every time at that range, but you'd still make quite an impression.