According to this video tests your default damage falloff distance is wrong.

I calculated with 32 cs2d pixels = 64 csgo units.
If the players has a distance of 64 pixels (=128 csgo units) then your tazer doesnt do any damage.
dmg = TaserBaseDamage * (1 - distance / TaserRange) -- pasted out of your code
dmg = 500 * ( 1 - 64/64)
dmg = 500 * ( 1 - 1)
dmg = 500 * 0
dmg = 0
While the video says it does a damage of 163 on 128 csgo units (= 64 cs2d pixels).

The video gives us 5 points.
P1: 285; 64
P2: 163; 128
P3: 100; 183
P4: 99; 184
P5: 0; 232

Edit: It even provides a 6th point and more information like hitting someone in the back makes less damage.

So you can create a function like this:
y = ax^4 + bx^3 + cx^2 + dx + e

I tried to insert the 5 points to get a linear equation system to calculate each variable a,b,c,d,e but when I try to insert the value my values never fit.
I use an online calculator* for this.

This website uses the Gaussian Elimination Process

Below you can see "Allgemeine Lösung: x = {}" which is in theory a (above most), b, c, d and e (lowest most) so you know how the function looks like.
But when I test the values I dont get the right y-values whatsoever.

If you are able to calculate the correct values you can make an almost real CSGO like tazer by using something like:

I hope this was at least a little bit useful.