Smoothbore vs Rifling

G

godofthunder9010

Active member
Somebody help me out here. Numberous tech specifications for tanks list Smoothbore for the main gun. To my brain, that means Non-Rifled, thusly the fired round does not spin and is less accurate over long distances and loses the bonus of spin at impact. But so many modern tanks list Smoothbore, I think I'm missing something.

Can anyone shed some light on this for me?
 
Like I siad, you loose muzzle-valocity with the Rifled guns....The older guns(105mm) mostly were rifled, but I think they gave it up with the 120mm ammo being so powerfull anyways...Costs more to rifle..... The Russians had rifled guns 2(as I know) up to the 115mm which was a smooth bore. The brits used a 120mm rifled on the Chieftain NBT, making it the first western tank with a 120mm, and continued using the Rifled 120mm on Challenger I and II.
 
The smoothbore (non rifled) 120mm barrels are used to fire APFSDS rounds. These are Armour Piercing Fin Stabilized Discarded Sabot rounds. The spin is, obviously, imparted by the fins. The Sabot is the waste of the shot that makes the round 'bullet' shaped for firing and is discarded soon after the round has left the muzzle. This leaves the round looking like a large dart. It is inert and its power is in the energy that the round has - it is made from depleted uranium. This is the round that has recently caused some controversy.

Oh! To my knowledge - the Challenger is fitted with a 120mm smoothbore gun and fires the APFSDS round.
 
SHERMAN said:
Like I siad, you loose muzzle-valocity with the Rifled guns....The older guns(105mm) mostly were rifled, but I think they gave it up with the 120mm ammo being so powerfull anyways...Costs more to rifle..... The Russians had rifled guns 2(as I know) up to the 115mm which was a smooth bore. The brits used a 120mm rifled on the Chieftain NBT, making it the first western tank with a 120mm, and continued using the Rifled 120mm on Challenger I and II.
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I remember your response Sherman and I appreciate it. I just want to get as much data, both for and against. Since the Brits are doing it, I assume there is a good reason to rifle the barrel of the main gun.
 
Well, I think they just kept it from the Chieftain....I think that when they were first with the 120mm(Chieftain) they kind of got fixated with the rifling, while the other MBT makers had time to think it over...When the Challenger I came out it got baiscally the same L11 120mm rifled main gun as the Chieftain...So, when they had to decide what to do for a main gun for the Challenger II, someone probably stood up and said "We already got a rifled 120mm, and our other tanks have it...We might as well improve it a bit and stick it on..."
They now wish to develope a Smooth-Bore to replace it:
Challenger 2 is equipped with an L30, 120mm rifled tank gun from BAE Systems RO Defence. In January 2004, RO Defence was awarded a contract to develop a new smoothbore 120mm gun for the British Army Challenger tanks. A technical demonstrator will be produced by 2006.
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http://www.army-technology.com/projects/challenger2/index.html
 
Do you know what the life of a Chieftain barrel is, Sherman? It is not long about 200 round equivalents, if memory serves (somebody can correct me here). Smoothbore barrels last longer because the metal of the barrel is less likely to migrate towards the muzzle. This is what limits the life of the rifled barrel (120mm AP rounds are quite heavy).

This migration causes a narrowing of the bore at the muzzle end of the barrel, which will eventaully prevent the passage of the round. This would have a catastrophic effect on the barrel and, probably, the crew.

I was sure that the Challenger is fitted with a smoothbore and will check. I have definitely seen APFSDS ammunition though and due to the mass of the round (have you ever pick one up?) - would doubt it being fired through a rifled barrel (exasperate the migration problem). My point is - there must be some smoothbore barrels out there in the British Army and the only logical place is in the turret of a tank. The only MBT we have is Challenger - QED!

Ok! I have read your page and all I can say is 'That is bloody typical of our Gov's attitude' I would be interested to learn what the life of the barrel is though. As an aside did you know that in theory, you could own a tank with a smoothbore gun on a shotgun licence. I say 'in theory'!
 
LOL@Shotgun....

As to the Life span of a rifled weapon, that is true.....Did not consider that up to now...That would explain the move to smooth bore guns as the ammo is getting more and more powerfull, causing more tear and wear on the barrel. But, you should think about this: The UK came up with the Centurion, and after coupeling it with the L7 Rifled 105, had what was arguably the best tank in the world at that time. Than they came up wih the Chieftain, and again with a 120mm gun had what was(with all its little problems) argaubly the best tank in world. So, why souldent they go with the rifled...It was the natural thing to do.....All that into consideration, the brits again can claim that they have the best tank in world....Even if the Germans, Americans and Israelis will get mad.
 
The Challenger series do indeed use a rifled gun. Reason why they can still use HESH, which require spin to work properly.
 
So what is the consensus then? If the rifled barrel on British tanks a significant drawback or a significant advantage? Do they lose range with the loss of muzzle velocity, or does the spin compensate for this?
 
The Challenger rifle is the best main tank gun in the world. Spin stabilized rounds are inherently more accurate then fin stabilized ones, the lack of fins on the round mean it goes faster, and the gun can fire HESH, a great infantry support shell.

Too bad rifled tank guns are extremely expensive, as the rifling needs to be well made. They don't last long, the rifling wears out really fast. That's why the Brits were looking to go smoothbore, but didn't for some reason.
 
Ive talked about this with a very experienced armor core officer. he told me that this discusion is very old and dates back to the first 120mm...However, I would consider the fact that most armies prefer the smooth-bore to the rifling as some sort of a conclusin. The fact that the brits are now searching for a smooth bore is also a good indicator that the smooth bore is probably superior.
 
The reason the British *were* switching to smoothbore is totally cost related. Rifled guns are expensive, the ammo is expensive, and they both are not NATO compatible. The Brits aren't switching to smoothbore anymore, they retaining their rifled guns.
 
Kozzy Mozzy said:
The reason the British *were* switching to smoothbore is totally cost related. Rifled guns are expensive, the ammo is expensive, and they both are not NATO compatible. The Brits aren't switching to smoothbore anymore, they retaining their rifled guns.
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Ya see! This is where I was fooled :) . Normally it would take at least twenty year for them to effect a 'U-turn'. I knew that I had been taught and seen this stuff in the late 80's/early 90's. Sorry for bein' outa date :roll:
 
Well, seems to me that a 120mm rifled barrel is a potential problem as it has a good chance of wearing out in the middle of extended combat. Significantly greater chance than a smoothbore. That could make it a pretty big liability in exchange for any advantage that it provides.
 
godofthunder9010 said:
Well, seems to me that a 120mm rifled barrel is a potential problem as it has a good chance of wearing out in the middle of extended combat. Significantly greater chance than a smoothbore. That could make it a pretty big liability in exchange for any advantage that it provides.
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I'm pretty sure the Brits make sure their guns are in top notch condition before going into combat.
 
The only reason the British MoD was considering switching to a smoothbore gun was financial.

Modern MBT ammunition is reaching the end of it's life and it is time to start developing the next generation. This costs money. The smoothbore gun operators mainly Germany and the US will join together to split the development costs. Britain however would have to develop a next gen rifled round on it's own, and with the end of the Cold War the MoD can't afford too. Also British ammo is not NATO standard so that is an added incentive to change.

The British Army still consider the rifled 52cal 120mm the best MBT gun in the world. The M1A2 and Merkava both use shorter 44cal guns, and while the Leo2A6 uses a 52cal they don't use DU ammo like the Challenger.

Side Note: One of the main reasons why the Challenger 2 came bottom in trials for the Greek Army, is because of the non-NATO standard gun, which automatically ruled it out of contention.
 
Quick note about rifle via smoothbore.

The reason most Nations go for smoothbore is that sabot and heat rounds work better when no spin is placed on them ( the French had a heat round with ball racers so the shape charge wounldn't be spinning when fired from their 105mm rifled cannon.)

The reason Uk forces have had a rifled gun is because of better range and hit probablity with normal high explosive rounds. In WW2 75% of all rounds fired were high Ex not anti tank. Thats why their kept normal 75mm gun shermans and not all 17pdr firflys.

UK had a 140mm rifle planned to replace the charm3 L30 gun. But this is not due untill the next tank. So they are looking a replacing the rifle with smooth bore due to better performance anti tank and cost of the rounds.

Final note in Gulf War 1 the UK tanks stopped using sabot rounds because they could hit and destroy the Iraq tank at 4km + with their old hesh rounds, far out ranging their sabot round.
 
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