# Would a gun with this barrel shape generate less recoil?

1. Jan 24, 2016

### y2jayy

I was wondering whether the following gun barrel shape would generate less recoil.

Imagine that we have a bunch of L-shaped pipes which are closed on their long end and open on their short end. Take 4 of these pipes, and join them up along their short parts so that they form a plus-sign shape when viewed from above. Then, this 4-pipe structure is attached to the barrel of a gun and, in effect, made into the gun's stock.

When the gun is fired, as the bullet is pushed forward by the gas, the gas is pushed backwards. But then the shape of the "L-shaped piped barrel" would divert the direction of the backward-moving gas along the axis perpendicular to the axis of the gun's barrel. Finally, the gas would collide with the closed ends of the 4 pipes, but would do so in a way that the force imparted would, first, in the component parallel to the barrel of the gun, be 0 or close to it since the recoil force would be acting on a surface (the pipe's end) parallel to the barrel of the gun and in the component perpendicular to the barrel of the gun, also 0 since each of the 4 vectors that would point outward along the pieces of the "plus sign" would add to 0.

Wouldn't the above mechanism damp the gun's recoil without requiring the gases to be discharged from the gun, as in the traditional recoilless rifles?

2. Jan 24, 2016

### Chip

No. The situation still reduces to the principle of the conservation of linear momentum, and you will still get a kick. The forces you speak of will cancel, but you will still have the impulse at the back of the gun, ie. in your case at the locations of the L curvature.

If you want a gun without recoil, you need to shoot 2 equivalent bullets simultaneously in opposite directions...or something equivalent.

3. Jan 24, 2016

### Staff: Mentor

4. Jan 25, 2016

### y2jayy

So you're saying that there would be the exactly same amount of recoil in the gun I described and a "normal" gun (all other things between the two guns being the same of course)? Or that the recoil will be less, but still greater than zero.

I understand what you mean by the impulse at the back of the gun being imparted to the L-curvature. But assuming that the gases are still moving at nonzero speed (which seems a totally valid assumption), surely it means that some of the momentum of the gases is dissipated in a direction perpendicular to the barrel of the gun, and thus not affecting the recoil...?

5. Jan 25, 2016

### Rx7man

I think a muzzle brake kind works on that principle, but deflecting exhaust gasses to the side rather than letting them go forward and contribute to kick

6. Jan 25, 2016

### Staff: Mentor

It works! At least the OP's post was on the right track. The WWII recoil less rifle used this principle. I provided a link in #3.

7. Jan 25, 2016

### Ranger Mike

excellent weapon..but had to use string to bore sight it..and ..it was VERY heavy to hump with your other gear...but was great weapon for the Infantryman

8. Jan 25, 2016

### Staff: Mentor

Huh? I don't understand that.

9. Jan 25, 2016

### Ranger Mike

Thank you for the nice reply and we should leave this subject to the past please.

10. Jan 25, 2016

### gjonesy

Muzzle brakes and recoilless rifles use redirection of the expanding gasses, the same as in the op's question but those are not closed systems, that gas and energy has to be released in some manner for it to be effective in reducing recoil. Some muzzle brakes aren't so much designed to reduce the kick of a weapon as they are used to stabilize the weapon itself. But if you could design a weapon in a manner like that, (But so the gasses could be expended slowly) it would also effectively suppress it.