Originally Posted by NMGlocker
For every action there is an equal and opposite reaction.
The force is equally distributed to the gun and the bullet at all times, from the instant of ignition to the moment when the bullet is no longer containing the gas pressure behind it (the instant it leaves the barrel). As soon as the gas seal is broken by the bullet leaving the barrel, the recoil force ends.
What you are seeing in slow-motion photography (when the gun moves after the bullet leaves the barrel) is the delayed application of the force on the gun due to the gun/shooter combination having more mass than the bullet.
If you clamp the gun into a solid structure of greater mass than the energy generated by the round being fired, the structure would not move at all.
Now, if you take and apply a load cell to measure the forces generated you'd see the steady increase in force applied up until the bullet leaves the barrel and then an instant loss of force.
A simpler way of testing this yourself is with a blowgun.
You blow and the instant the dart leaves the barrel the pressure required to "shoot" it is relieved.
There is no recoil force applied to the gun after the bullet has left the barrel... NONE.
There is no firehose/rocket effect... NONE.
I could see that post being made a sticky all on it's own, let alone the rest of the thread!