Originally Posted by PublicSafety400
Well, I'm willing to take the word of a physicist over the limited knowledge of all the M14 experts here. Here is a link to an excellent video that explains why recoil does not occur until the projectile has left the barrel. Conservation of momentum is part of Newton's third law in a closed system it is not in contradiction to it. https://m.youtube.com/watch?v=1-s8NZ8xKW0
PublicSafety400, The rifle starts moving as soon as the bullet start moving. Physics dictates this.
The video in your post tries to explain this but does a bad job.
v1 x m1 = v2 x m2 where the ones are the bullet and the twos are the rifle.
Total momentum of the system is unchanged, true. The momentum of the bullet/gas is not unchanged. Neither is the momentum of the rifle. They are equal but at opposite directions.
11g (~155gn) bullet leaving the rifle at 2700fps from a 4.5kg (10lbs) rifle:
0.011kg x 2700fps = 4.5kg x 6.7fps
When the bullet reaches the tip of the barrel, the rifle would be moving backwards at 6.7 fps if not supported by the shooter/rest. In reality, some of the weight of the powder should be added - more of rearward momentum.
Most of the time when I call the shot it is a bad shot as I saw the rifle moving as I broke the shot, particularly in offhand. Sometimes in prone if I pull the trigger rather than squeeze.
Off rest, with scope, i find it hard to call the under recoil movement of the rifle. The harder the rifle recoils, the more it moves while the bullet is still in the barrel and the more important it is to hold it exactly the same every shot.