Understanding Rifling: How Does it Work?

[vin300]

I'm trying to grasp how rifling works. I think I understand gyroscopes. The purpose of rifling must be to prevent horizontal deflections.

 

[turbo]

You might want to Google on Whitworth rifles, perhaps the most extreme example of rifling in the past 200 years. Those rifles were very accurate. The cost of producing them made some armies reluctant to adopt them, though quite a few saw service in the US confederacy.

 

[SteamKing]

The rifling causes oblong projectiles like bullets and shells to spin as they travel down the bore of the gun. The spin is rapid enough to give these projectiles enough rotational inertia to stabilize them in flight and to keep them from tumbling end over end. Rifling became necessary as guns large and small switched from spherical projectiles to the non-spherical versions common today.

 

[vin300]

If the axis of spin is x, gravity provides couple around axis y, the resulting gyroscopic stabity would prevent deflections in a horizontal plane, not in all three dimensions.

 

[sophiecentaur]

If the axis of spin is x, gravity provides couple around axis y, the resulting gyroscopic stabity would prevent deflections in a horizontal plane, not in all three dimensions.

Any couple due to gravity cannot be because of gravity alone. There must also be some other net aerodynamic force acting away from the centre of mass to provide the other contribution to the couple. Afaik, the main couple is due to aerodynamic forces, which would cause the bullet to tumble in its flight. This could cause a spiral path for the bullet, leading to inaccuracy and also loss of speed.

 

[Baluncore]

Rifling causes a bullet to spin about it's longitudinal axis which stabilises it in flight. When a bullet grazes a hard object it becomes deformed on one side and so begins to radiates a distinctive sound frequency. That audio frequency is the rate of rotation due to the rifling.