This magical thing called "recoil"....

Have a legend for that equation?

Main difference is in the efficiency. That 12.5kJ is the theoretical potential. Much, much less energy than that actually goes into effect though. The guy for that video doesn't provide the efficiency of the rifle. The one I posted earlier, the man-portable one, was getting roughly 3%.

Did you guys ever stop and think that maybe it's called a gauss rifle for some other reason that what you think?

ENERGY AND MOMENTUM ARE DIFFERENT!

What i said was "The reason is that momentum (in this case) is purely factor of time, while energy is a factor of distance." Key phrase being "in this case" since the barrel length is fixed (and travel distance, in most other situations, is not).

I don't want to sound like a dick, but I am posting because this is an extremely common misconception. I've spent years studying and coding physics so, please trust me, energy != momentum... ever, in any situation, even if they are the same number. Even on the moon, mars, alpha centauri, and especially not while approaching the speed of light. Energy is measured in joules, AKA a newton * a meter, while momentum is measured as a newton * a second (see how it doesn't have it's own unit? That is because physicists know momentum is silly). Strictly speaking both energy and momentum are both vector quantities as they are a product of velocity.


FORCE AND ENERGY ARE DIFFERENT!

If you don't keep this in mind you sound really dumb to someone who does. Think of a 200ton truck rolling into you at 1mph vs a 2 ton truck smashing you at 100mph. Should be pretty intuitive which one you want to be hit by. Even though their momentum is the same, one is significantly more dangerous. These are facts, based on physics. If anyone doesn't believe in physics please explain to me how we send rockets to other planets before making another post in this thread.

force * distance = work ( http://en.wikipedia.org/wiki/Mechanical_work ),
force * time = impulse (AKA change in momentum - http://en.wikipedia.org/wiki/Impulse_(physics) )

Not to invalidate anything else you said, it seemed accurate. The 45 vs 40 comparison was the first thing that came to mind but it's certainly flawed. For reference though I have compared an XD40 and XD45 and the same holds true (very similar weight and identical materials). Also, the firing chamber pressure for a .45 is definitely, undoubtedly, lower than a .40. The bullet spends more time in the barrel, it is being pushed for *longer* (because it is accelerating slower, being a more massive object), therefore less pressure is needed to achieve the same momentum.

Anyways, i was hoping I could drop some real physics into this conversation and get everyone to shut up about gauss weapons vs recoil but that clearly didn't work.

The point is still unarguable, smaller projectile with comparable momentum (needed for range and penetration) will require more energy. More energy == more felt recoil. Lower energy with the same momentum means more time to control the recoil, which means your puny human muscles can do a better job at it (less peak force required).


MOMENTUM AND FORCE ARE DIFFERENT!

Someone doesn't understand how Newton's Third Law of Motion works.

Someone doesn't know how to read a thread

Or if you are too lazy to read, Newton did not say "For every action there is an equal and opposite recoil"

You still don't get it.

Any force that pushes a projectile has to have a countering "pull". It doesn't matter if it is a magnet or expanding gas. The Magnet is pushing the bullet down the barrel, the bullet is "pulling" the gun.

You can work up some Nanite Magic to counter the force, but the same argument could be made for standard projectiles too.

Wow I haven't read every post in this thread but I approve of all the cool information!

Try discovering the magical thing called "control", it works very well I hear.

**** it, its a video game, this **** works how the devs say it works, how about that.
If you dont want roughly double the damage per bullet of the T9 Carv, then im fine with them "fixing" your recoil.

I think your NC comrades will agree you {OP} make your faction look bad...

Confuzius says: "its good to meet girl in park but its better to park meat in girl!"

You are absolutely correct, whether you use a magnet or expanding gas there is an equal and opposite reaction. Please read the thread, that's not in contention.

Recoil is simply the Reaction force applied by the bullet to the gun acting upon the system of gun and shoulder/mounting.

Accelerating a bullet, whether by expanding gases or electro-magnetic forces, applies an equal and opposite force to the acceleration device (gun). This force is the recoil. Even a coilgun has recoil because as the magnets pull on the bullet, the bullet pulls on the magnets (equal and opposite force). Because the magnets are firmly attached to the gun, the force on the magnets is transferred to the frame of the gun, and then to whatever is holding the gun, as Recoil.

All the videos so far show either some evidence of this reaction force, or the energies being to low compared to the mountings of the guns to show it. Even the Asymmetrical Capacitor Thruster mentioned in the NASA paper uses Newton's action-reaction principle.

Some of the reasons modern guns do not use tiny, very fast bullets are partly due to the limitations of the gunpowder reaction. The explosion is simply not fast enough to lend the speed required to the bullet. Another is the barrel length required to properly transfer the energy of a large cartridge to a small bullet.
A sufficiently powerful gauss gun could get by both of those restrictions, but it would still run into the issues of energy loss and penetration.