From Rifled to Smoothbore. Why the Switch?

[Icehawk]

From what I have read, modern battle tanks seem to all have abandoned rifled cannons infavor of smoothbore guns. What is the reason for this? Does it have better range, or accuracy or something? I always thought that having a rifled barrel was better because it spun the shell allowing it to travel through the air better.

I have never been able to find a reason for the change and its just been puzzling me for a while.

[Vympel]

A rifled tank cannon assists accuracy at long range by spinning the round but at the cost of a loss of pressure- reducing the velocity of the round. However, the reason for the 120mm smoothbore for the M1A1/A2 and Leopard 2 series is for the APFSDS round- these are not stable in flight if they spin like a bullet, so you have to shoot it through a smoothbore or it will tumble.

The principle is supposed to be the same as shooting an arrow through a sandbag that will stop a bullet.

The first smoothbore tank gun in the world was for the T-62 tank with 115mm gun- it fired a sabot round.

[Sokar]

The switch to smoothbores came when they developed the SABOT anti-tank round. If your unfamiliar with these, they are long-rod armor penetrators, essentaily a long thin dart of ultra-dense metal(preferably depleted uranium) that is considirably smaller than the bore of most current cannon(on the 120mm M1 main gun , the SABOT penatrator os only 45mm) This long rod is encased in a 'sabot' shell which harnesses the energy of the propellant as the round travels down the barrel. After exiting the 'sabot' (which is French for shoe) falls away from the penetrator. Rifled versions of these rounds existed for the 105mm Lahiti on the first gen M1's and M60's , but without a sophisticated sabot assembly that kept the rod stationary in the bore, the rifiling imparted a wobble to the round that severly hampered their long range ability.

[Sea Skimmer]

The introduction of fin stabilized ammunition which removed the need for a spin for accuracy and barrel wear problems with the growing velocity and working pressures of tank guns. Those where the main reasons, but ammo was part of it.

Discarding sabot AP rounds also work better when there stable, and HEAT can't have a spin at all. The fire a HEAT shell from a rifle gun there has to be an external sleeve that spins freely of the warhead within. You then also need fins to remove any spin that is imparted. The result is the round has a much smaller explosive charge then would be possibul if you didn't need all the anti spin gear.

[Sokar]

Greetings Treadheads!

[Vympel]

I should also point to add to Skimmer's point that when the T-64's 125mm smoothbore came out way back in the early 70s, the prime weapon was HEAT ammunition.

[Sokar]

That was also to facilitate the early T-64's attempt to have a main gun launched anti-tank missile, a silly idea in the end. But the T-64 was designed in the era of the undefeatable HEAT warhead , so on paper it sounded good.

[Pablo Sanchez]

That was also to facilitate the early T-64's attempt to have a main gun launched anti-tank missile, a silly idea in the end.

Not when it's guided, capable of putting out consistent hits at three klicks, and able to shoot down those $#&*ing helis in the hands of a skilled operator

[Vympel]

Not when it's guided, capable of putting out consistent hits at three klicks, and able to shoot down those $#&*ing helis in the hands of a skilled operator

Yup. The Kobra (AT-8 SONGSTER) and Refleks-M (AT-11 SNIPER) may have substantially increased the cost of the tank (so much so that dedicated no-ATGM versions were made- the T-64B1, BV1, T-72B1) but they are effective.

[Sea Skimmer]

That was also to facilitate the early T-64's attempt to have a main gun launched anti-tank missile, a silly idea in the end.

Not when it's guided, capable of putting out consistent hits at three klicks, and able to shoot down those $#&*ing helis in the hands of a skilled operator

*Exterminates missile launching T-64 unit with TOW from above and behind*



AH-56 Owns your puny tanks

[Vympel]

AH-56 Owns your puny tanks

That helo sucked ass, dude

[Sea Skimmer]

AH-56 Owns your puny tanks

That helo sucked ass, dude

Silence mortal fool, hopeless complexity in advance of available technology does not concern me.



If we built it today it work work just fine, until it gets shot at anyway.

[CmdrWilkens]

AH-56 Owns your puny tanks

That helo sucked ass, dude

<snip>
If we built it today it work work just fine, until it gets shot at anyway.

Bah, we shouldignroe pesky things like combat reliability and survivability I mean who needs that anyway?

[Sea Skimmer]

That helo sucked ass, dude

<snip>
If we built it today it work work just fine, until it gets shot at anyway.

Bah, we shouldignroe pesky things like combat reliability and survivability I mean who needs that anyway?

Exactly, when you have a shit load of TOW's and guns and 300 knot speed its not like anythings going to even dare to shoot at you.

[Pablo Sanchez]

Exactly, when you have a shit load of TOW's and guns and 300 knot speed its not like anythings going to even dare to shoot at you.

Captain, I suggest that we undertake several low-speed, low-altitude passes over their triple-A batteries in order to impress upon them the enormity of our firepower.

[Pablo Sanchez]

Bah, we shouldignroe pesky things like combat reliability and survivability I mean who needs that anyway?

Only those clumsy fools who actually have to fly it, plus (maybe) the people it's supposed to be supporting.

[Eleas]

Exactly, when you have a shit load of TOW's and guns and 300 knot speed its not like anythings going to even dare to shoot at you.

Captain, I suggest that we undertake several low-speed, low-altitude passes over their triple-A batteries in order to impress upon them the enormity of our firepower.

You know, the weird thing is I can actually hear some stiff-upper-lip british commander say something like that.