Would a gauss rifle based on generated magnetic fields have any kickback? In the case of currently developing Gauss rifles, in which a slug is pulled down a line of electromagnets, facilitated by a micro-controller to achieve great speed in managing the switching of the magnets, does the weapon firing produce any recoil? If so, how would you go about calculating that recoil?  
 A: Simple answer when you think about it:
You are imparting a force to accelerate the slug, so you're going to get an equal and opposite reaction. In a normal rifle, the explosion accelerates the bullet rapidly and you get recoil.
In a gauss rifle, the acceleration will be a bit lower, but for a slightly longer time (the entire length of the barrel), so for the same muzzle velocity you will be able to calculate the recoil in the exact same way.
A: If the Gauss rifle shoots a projectile with exit speed of $v_1$ and mass $m_1$, then its momentum will be:
$p=m_1v_1$.
Because of momentum conservation law, the rifle will have the same momentum in opposite direction. If the rifles mass is $m_2$, the rifle will start moving in the opposite direction with end speed of:
$v_2 = \frac{m_1 v_1}{m_2}$.
But, as the projectile is accelerated for longer time than in a gun, the force acting from rifle on its holder will be lower because $F=\frac{dp}{dt}$ 
A: About the magnitude. This source claims 2056m/s exit speed, this one around 2382m/s (mach 7).
I have no idea what a personal reilgun's projectile weight should be. Let's take a random pistol round: 7.5g.
Gun length? Let's pick 1m. Gun weight? Let's pick 3kg.
v_gun = - p_projectile / m_gun =
(2382*7.5*(10-3)) / 3 =
5.955m/s

acquired over one meter of travel at let's say constant acceleration.
x = v_0 t + (1/2) a t^2
2 = a t^2
t = sqrt(2/a)
where a = v / t
t = sqrt(2t/v)
t = sqrt(t) sqrt(2/v)
sqrt(t) = sqrt(2/v)
t = 2/v
t ~= 8.4ms

Now the (obviously constant) force is going to be
F = m a
a = 5.955m/s / 8.4*10^-3s = 7089m/ss
F = 3kg * 7089m/ss = 21267N

A typical pro boxer's punch is 5000N. So we are going to need lighter bullets. I wonder what would happen if you shoot this thing in a sandstorm. Or indoors.
