Why smoothbore main gun?

[Mark IV]

<BLOCKQUOTE>quote:</font><HR>Originally posted by :USERNAME::

I believe the US should keep 105mm Abrams around just do to the fact they can carry WP and other rounds the later version 120mm cant.<HR></BLOCKQUOTE>

Why couldn't a 120mm fire WP? What would the technical reason be?

[:USERNAME:]

No technical reason. Just no round available. 120mm carried APFSDS and HEAT for awhile only. Now they have a better HE/HEAT round and i believe a top attack ammunition also. There is only so much room and the mission of the Abrams is really to kill armor so AT rounds fill the slots.

Indirect fire supplies most smoke missions I suppose. But its always nice to be able to put WP on a target directly IMO.

Lewis

[Murx]

USERNAME, You are right on the space & use of MBTs like M1A1 Abrahams & Leopard 2 using smoothbore they are tank-killer.

And for the smoke, we still have that on the tank, there is a kind of mortar with 6 shots and 2 flanks(3 shots each) attached to the turret. So one can fire either a single smoke round approximately 30m in front of the tank or a smoke wall of three smoke rounds in 60 or 70 degree right or left of the tank.

The Leopard 2 carries 49 rounds if I remember right and has only 15 in turret, thus handy in an engagement. With 80% first shot/hit rate and normally 9 rounds APFSDS and 6 HEAT that would mean 7 tanks - more then most nations tank platoons have tanks, German tank companies have currently 13 tanks if I'm right (dunno if they changed ToO&E again).

But the real problem with ammo is - reloading a different kind ! A good loader can reload in under 9 seconds a fired gun, but you need nearly 30 secs to unload & reload if no problems occure (and problems tend to happen when you dont need them ). OK, the Gunner can make a 'hot' unloading by just firing the round in the gun but thus you loose valuable ammo you might need later.

AFAIK the only *new* ammo that will really be used for the 120mm smoothbore will be range-ignited ammo for airborne (helicopter) targets. So when you rangefind a helicopter the round will explode near it thus disabling it even if it didn't hit (same system behind WWII AA-Guns - but they were manually set for height/time of flight).

Other ammo for the 120mm I have heard of but can't validate is HE for bombardment - inaccurate but hey it's just like arty in directfire...

And something called APER (antipersonell I think) rounds that wont damage a tank but the shrapnell would be a horror for infantry, used to give firesupport to friendly AFV that are in close combat/being stormed by OPFOR infantry with satchelcharges/magnetic mines.

murx

(my 0.02 Euro )

[This message has been edited by Murx (edited 06-17-2000).]

[Guest Big Time Software]

Lewis mentioned the main benefits of a muzzle breaks. It was also good for directing the expelled gases in a more orderly fashion. I'm not sure how usefull this was for most vehicles, but when the Germans developed the Jagdpanzer IV they initially armed it without a muzzle break. Because the gun was so low to the ground it had the potential to kick up a lot of dust. Apparently this was fixed when they put the muzzel break on later models. IIRC this happened for both the JPZ IV and JPZ IV/L70.

Steve

[Guest Big Time Software]

How come the Abrams carries both APFSDS and HEAT ammo? It seems like they accomplish the same mission. I was under the impression that HEAT was best suited to low-velocity guns, for whom AP wouldn't be very effective. But clearly the 120mm has excellent velocity/APFSDS - so what's the advantage of HEAT in this case?

Charles

[Trooper]

If you shot up a BTR-80 from the side with an M829A1 or similar top-of-the-line KE round, it has a good chance of going in one side, and right out the other without doing a heck of a lot of damage. (Kills anyone in the way, maybe a little spalling, that's it). A HEAT round is a little more devastating inside a soft-ish-skin vehicle, you have this super-hot plasma stream running around.

The other thing to note is that a HEAT round's effectiveness generally remains constant with range, whereas a KE round becomes less effective the further away the target is (Drag slows it down, reducing the overall energy imparted), thus at extreme ranges, HEAT may be more effective against armored targets than KE. That's one reason I heartily approve of the British concept of a rifle with HESH. (HESH was the default ammo in Challengers in the Gulf)

[Mattias]

Steve,

On the muzzle breaks.

From May 44 onwards muzzle breaks on the JgPz IV were not fitted on production vehicles, for the reasons you mention, in the field they were already removed by the crews.

On the Pz IV/70 it was never fitted to begin with, nor was it on the Hetzer.

All barrels seems to be able to take a muzzle break though, no doubt as there was no difference between the tank and SPG guns in production.

In post war pictures a muzzle break is often seen on these vehicles. In the case of display vehicles I suspect it is to make them look more butch.

On the other hand Swiss post war Hetzers had a muzzle break fitted, most probably to reduce wear in peace time training though.

M.

[This message has been edited by Mattias (edited 06-18-2000).]

[T-34\85]

Since the Abrams doesn't carry anything except tank killing ammunition (same goes for Leopard, LeClerc and Challenger 2 ... the latter of which uses high explosiove squash head rounds as well) ... then it seems like they've pretty much cut out the infantry killing role of the tank ... which leaves killing infantry to, well, the infantry, with no real heavy support save artillery ... which isn't all that timely or accurate ... Russian tanks on the other hand carry an extremely heavy high explosive armament ... more than anti-armor rounds actually judging by the T-90's ammo load (I read somewhere that western tank guns are charachterised by their excellent anti-armor capability while soviet guns by their high explosive power). Tanks on the western side have pretty much lost their breakthrough role it seems.

[Harold Jones]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Trooper:

If you shot up a BTR-80 from the side with an M829A1 or similar top-of-the-line KE round, it has a good chance of going in one side, and right out the other without doing a heck of a lot of damage. (Kills anyone in the way, maybe a little spalling, that's it). A HEAT round is a little more devastating inside a soft-ish-skin vehicle, you have this super-hot plasma stream running around...

<HR></BLOCKQUOTE>

I saw this myself in the gulf, my tank and 3 or 4 others engaged a Cascavel (French made armored car with a 90mm) with APFSDS rounds all the rounds hit but there wasn't a whole lot of apparent target effect. Since US doctrine calls for engaging until the target burns or changes shape my tank reengaged with one HEAT round. The effects were immediate, the turret blew off (probably the result of ammo cooking off) and so did most of the suspension components on the side of the vehicle facing us. A HEAT round will tend to penetrate the armor and then expend the rest of its energy inside the armor envelope. For a sabot round to be truly effective you need a target of a certain mass otherwise they just blow through both sides with minimal damage. HEAT rounds are also useful against bunkers and troops although an argument can be made that carrying a few HE rounds would make sense as well.

[argie]

Harold, the Cascavel (EE-9, IIRC), was Brazilian made, not French...

Ariel

[Murx]

T-34/85, You forget that nowadays we have no Infantry anymore, they are all mechanized infantry, thus having their own support tank - Marder, Bradley and lots of others I don't know. It's far more efficient to use high ROF weapons (like HMGs and small caliber guns (20mm MK)) for firesupport then the big ones.

You can better adjust the amount of damage you want to make (sometimes you have own troops in/near targetzone so you don't want use HE on the enemy AND your troops - else they wont like you much )

The reason why there is both HEAT and KE (APFSDS) is that HEAT will have little effect on most odern MBT-frontarmor. + most modern tanks have a shaped armor thus HEAT more easily glances off. For APFSDS to loose power due to range - quit ridiculous, OK they loose power but for combats up to 4Km that reduction is less to mention. On trial-shootings with the 120mm smoothbore they shot at T-62 tanks at 1Km, the round went straight through it (and the whole engine block!) most times and still buried itself several meters (over ten) in the ground (there were hills behind the targets for safety reasons).

When it didn't went through it got caught inside the turret and flying erranous in circles ricochetting from the round interior. Like a big Mulinex. Don't let me tell what happened on the pig-trials they made both with enemy tanks & the Leopard 2 ...

murx

[Mark IV]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Murx:

Don't let me tell what happened on the pig-trials they made both with enemy tanks & the Leopard 2 ...<HR></BLOCKQUOTE>

Pig trials?

Tell us about the pig trials.

[:USERNAME:]

M1s carry HEAT as a multipurpose weapon. It has been designed to be AP and also antipersonnel. So SABOT rounds are for MBT usually and everything else, infantry, bunkers, light armor, buildings, etc get the HEAT treatment.

In certain high priority targets like radar vehicles, anti aircraft vehicles, HQ vehicles, a Sabot could be used to ensure a quick kill (its alot more accurate at range). The HEAT round is kind of shaped like a mortor round and when going down range I bet it has some funny flight characteristics.

The US has developed MPAT (multipurpose antitank?) that has better frag qualities (prox fused I believe) and can bother choppers that hang around.

MBT nowadays have reduced the number of rounds needed to get a kill but at the same time have reduced the number of rounds carried. So to have multipurpose rounds makes a lot of sense.

Lewis

PS Muzzle breaks also make life pretty unbearable for dismounts and anyone unlucky enough to be in front of the gun. Weapons like the PAK40 needed a shield for this reason as well as bullets and shrtapnel.

[Borgiax]

I've seen a post speaking of the Leopard II as a MBT using only mobility to protect against enemy shots. In fact, it was the Leo I, which, like his cousins designed in the 60s (AMX 30 etc) had steel armor unable to stop HEAT rounds. Leo II had Chobham armor able to stop HEAT rounds, just like "second generation MBTs" (M1, Challenger).

As for gun tubes, chrome lining is used on most modern tanks, including Leclerc's 120mm/52calibre smoothbore gun. It has an automatic loader too, able to perform unloading and loading in less than 6 seconds, at all speed and on all terrain. There are 22 ready to use rounds in the autoloader with 18 more in the hull.

[Trooper]

Oh, I'll admit, the overall energy loss at 4km is probably going to be quite small, but against something a little tougher than a T-62, it is theoretically possible that a round which might just penetrate at short range would bounce at long.

I still think that HESH is a better anti-bunker weapon myself, but I've never bothered going near the physics....

NTM

[Murx]

USERNAME, HEAT will sure not be used by NATO forces on infantry for one reason : Geneva Convention forbids combatants to use all calibers from 20mm and larger to be used on infantry. That is inhumane cause the wounds are either immediate death (not needed, not able to fight longer is enough) or are severe and leave lots of crippled veterans.

HEAT is not mortar shaped, if I remember right the arch of the firearc is less then 80cm on one kilometer. It's a direct fire weapon and cant be used indirect.

MPAT, prox fused rounds are only useful against *easily* damaged targets, a MBT from this or even several former on (probably including even Panther, KVs and even Matildas will just laugh). You still might be right that MPAT are multipurpose AT rounds but I don't know.

Borgiax, I just found out that the Leclerc has not the Rheinmetall 120mm! You can see that because the muzzlebreak (right word ?) is missing, it's the big part in the barrel.

As far as I know the Leopard doesn't use Chobham but a similar alloy.

And I suspect that you are not right for *reloading and loading* in 6 seconds. Reloading after fired in six seconds the next round in loader system without changing is sure possible. But rotating the loader to another ammo type + unloading (I even doubt that there is a autounloading mechanism as opening the breach and getting the round out of it is a real hard job both in power and difficile). But maybe I'm wrong and there is a unloading mechanism other then firing it will still take a considerable amount of time. (minimum would be the time needed to load but then rotating the reloader too)

Second thing on reloader ... another equipment that can jam. And I guess it's more complicated to refill the autoloader and takes more time. And a average loader can reload under all circumstances the gun can be fired + a good loader can load in under 4 seconds, tried it, done it [but only the first shot the next will take approx 6 seconds, but then you ignore some 'official rules' on loading protocoll] + you can't fire when driving cross-country at top speed (70Km/h and ore soetimes) cause the computer wont let you cause the stabilization is not fast enough, the gun alone weights nearly 5 tons !, the whole turret more then 16 tons with the additional armor most of the MBTs have by now, just make a short math on forces that occure here. So reloading at that speed is not needed .

Trooper: Bunkers ? They are completely silly today, you can't set up installations that can stand HEAT without notice thus airstrikes are likely to occure at those that are hard enough for HEAT . And mobile war is the name of the game today. Remeber Iraks troops completely bombed/rushed out couse they didn't move, they just dig their tanks in.

And Mark IV, just let me say the team that had to clean up the tank didn't loved the job, but after the test every equipment that was attached to the interior got a 6cm thick shock-dampener and no solid/metal is attached to the interior of the turret. It looked inside like, uh, you have a machine you make milchshakes with ? Yes? Try it with pigs...

murx

[This message has been edited by Murx (edited 06-18-2000).]

[GriffinCheng+]

On HEAT effect on "lesser-hard-targets": M1TP2 models this beautifully when you fire a APFSDS round on an AFV like BMP2, the target just sit dead even you are certain that you had been accurate. My best bet was always fire a HEAT round at first sight so it wouldn't play dead and fires an ATGM back.

On muzzule brake: is it the same reason why T34/85 did not have one? Without muzzule brake, would the AFV need longer turret?

Griffin @ work

------------------

"+" is just the beginning. Expect to see "GriffinCheng76", "GriffinCheng(105)" or "GriffinChengA3E8" more should Forum problems occur again

[Doug Beman]

That's part of the reason for putting muzzle brakes on guns, as they reduce the amount of recoil force, which reduces the amount of runback the gun requires to expend all the force imparted to it in reaction to the gun firing.

DjB

[Trooper]

I might point out that the bunkers encountered by the British forces in the Falklands were not targetted by airstrikes, but instead by Milan missiles. Now, I will grant you that the HEAT warhead seemed to do the job quite admirably, but then they weren't the toughest things in the world (sandbags and peat basically). Now if we go a step up, we still have works which are not worth an airstrike, but which may be a bit bigger than a HEAT round can handle, and HESH strikes me as being a lovely suitable round. All that HE nicely planted against the structure, then a bang should do damage.

LeClerc's gun is, if I recall, an L55 and longer than that on M1 and Leo2 (Thus resulting in higher muzzle velocity. However, the chamber is capable of taking the standard rounds as used by the Rheinmetall, this would make it the hardest-hitting anti-armor cannon on a production tank in the world if it ever used American ammo.

NTM

[Trooper]

A breach of ettiquette though it may be to respond to your own post...

Chap above said the LeClerc's 120mm is an L52, I said L55. If in doubt, go with him, coz I'm working from memory!

The 'big bumpy bit' in the middle of a cannon should be the fume extractor, not the muzzle brake. A muzzle brake is invariably on the muzzle (the end of the gun) Kinda hard to describe, your best bet is to take a look at the bulgy bit on the end of an M48's 90mm gun or a Panther's 75mm. The immediate exception that comes to mind is on most (Not the earliest) T-54 and T-55 (and copies) where the fume extractor is on the end of the gun next to the muzzle.

NTM

[T-34\85]

Well when I said infantry I did mean Mechanized Infantry ... but considering the Soviets pracitcally invented the Infantry Fighting Vehicle with the BMP I find it strange that Russian tanks still cary a heavy HE loadout while Western tanks in general carry hardly any, especially in the case of the US since the Bradley is pretty much a disaster if some critics are to be believed.

[Murx]

Trooper, thank You for correcting ( I wrote *right word?* in my post cause I didn't knew the right word. On some weapons the muzzle break & fume extractor are one part (like then MG3)

T-34, the NATO tends to 'over-arm' these vehicles with both armor & weapons. But (to my opinion) there is no need to build a allround tank-killer/infantry support vehicle. Like the PzKw III & IV, one for tanks and one for infantry support.

So they are most of the time too slow and can't keep up with the MBTs. But as a 'grunt' I bet I would prefere a bit more speed then relying on that armor on my 'support' tank.

murx

[:USERNAME:]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Murx:

USERNAME, HEAT will sure not be used by NATO forces on infantry for one reason : Geneva Convention forbids combatants to use all calibers from 20mm and larger to be used on infantry. That is inhumane cause the wounds are either immediate death (not needed, not able to fight longer is enough) or are severe and leave lots of crippled veterans.

HEAT is not mortar shaped, if I remember right the arch of the firearc is less then 80cm on one kilometer. It's a direct fire weapon and cant be used indirect.

MPAT, prox fused rounds are only useful against *easily* damaged targets, a MBT from this or even several former on (probably including even Panther, KVs and even Matildas will just laugh). You still might be right that MPAT are multipurpose AT rounds but I don't know.

murx

[This message has been edited by Murx (edited 06-18-2000).]<HR></BLOCKQUOTE>

Thanks for all the information. I am sure the world over that every shaped charge weapon will cease being fired at infantry.

I was refering to the actual shape of the HEAT projectile itself and not the shape of its flight path.

Please tell me more about the laughing tanks. I am not sure what you are saying but find you entertaining none the least.

BTW. I *HATE* when people here put words sandwhiched between astericks. Theres nothing worse.. except perhaps smiley faces between astericks * *.

MPAT can be prox fused or point detonating and can be used against light armor and probably laughing tanks.

Lewis

[Murx]

Hi Username, my reason for those asterix is that I'm German and don't always have the correct miltary technological word at hand.

Laughing tanks is a metaphor - just an image but I think You got a clue on that one

murx