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Friction vs. Smooth bore
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Does the friction induce much wasted energy in terms of having to cut the grooves of the bullet? Would not a 3 groove rifled barrel quicker than say a 5 groove rifling?
 
Posts: 1274 | Location: Saskatchewan, Canada.  | Registered: 22 August 2006Reply With Quote
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No, but having no rifling at all definitely makes for higher velocities. It is not the number of grooves that matters; the friction is very low, once the projectile is engraved. What takes all the energy is the very act of spinning the bullet. Two groove Springfield barrels have the same performance as 4.
One of the reasons our M256 120mm Tank Cannon is smooth bore and gets close to 5000 fps. Projectiles are fin stabilized, and for HEAT rounds, you do not want them to spin anyway. It disrupts the jet when it hits.
 
Posts: 12707 | Location: USA | Registered: 02 August 2009Reply With Quote
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Greener stated in his book a smooth bore was as accurate as a rifled bore to 60 yards. In addition, all things being equal (bullet weight and powder charge) a smooth bore would have higher velocity and less recoil; both due to the projectile not having to cut into the rifling. I've had smooth bores in 12 & 8 bore and accuracy was fine at the 50 yard targets at my home range.
C


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Posts: 6401 | Location: Willow, Alaska | Registered: 29 June 2009Reply With Quote
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when your talking about friction your talking about surface area.
cutting the engraving is something different, I'd call it distortion.

either way they are different forces.

anyhow.
you have to look at the total surface area affected.
12 very shallow lands and grooves.
5 rounded over or ratcheted lands.
4 square cut lands.
or three triangle shaped lands.

right.
all of them have surface area and all of them have to displace metal.
it's the total amount of metal moved and total amount of surface to surface contact your concerned with.
 
Posts: 3273 | Location: soda springs,id | Registered: 02 April 2008Reply With Quote
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