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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Twist rates on autocannon   General Military Discussion

Started 17-May by smg762; 441 views.
smg762

From: smg762

17-May

It's well known that cannon use different ammo types eg. HE and APDS.

If a 30mm cannon wants to use both HE , APDS and APFSDS, how can the same twist rate work with all those round s? Especially with APFSDS

In reply toRe: msg 1
RovingPedant

From: RovingPedant

17-May

You design the different ammunition to work out of the same gun.

APFSDS for a rifled gun typically has a slipping driving band, so the subcalibre projectile isn’t spun as much in the first place. Once out of the barrel the fins tend to kill what spin there is, to a point. The braking torque from the fins will be proportional to the square of the spin speed so the projectile will likely still be spinning slowly when it hits the target.

smg762

From: smg762

18-May

How do HE and APDS share the same barrel, don't they require different twist rates?

In reply toRe: msg 3
RovingPedant

From: RovingPedant

18-May

If APDS and HE are designed to be fired from the same barrel, they don't need different twist rates. 

APDS and HE have been fired from common guns since the mid 1940's 

You might not get optimum of either with a particular twist rate, but you can certainly define a twist rate and design APDS and full bore projectiles to suit that.

 

Mr. T (MrT4)

From: Mr. T (MrT4)

20-May

Even if the finned penetrator is understabilised by spin alone ,it has fins for stabilization. 

Much longer projectile is obviously not stabilized by same twist rate as the shorter non ap projectile

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