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Grundy
09 Mar 06,, 23:37
I was having a look at the Challenger 2 stats earlier and i realised it uses a rifled barrel whereas Abrams etc use smoothbore. Is there any particular reason for this?, how does a smoothbore shoot accurately because as i understand it especially with small arms to be able to shoot accuratley the barrel needs to be rifled to create spin

gunnut
10 Mar 06,, 00:02
Shells from smooth bore guns are fin stablized.

Horrido
10 Mar 06,, 08:59
Smoothbore does not wear out as quickly, so you get more practice and need to change/pay for barrels less frequently.

Simullacrum
10 Mar 06,, 13:01
Rifeld bore gives greater distance and pentetration then smothe bore.!

e.g.
180 Challenger tanks were deployed to Saudi Arabia for the Gulf War. The Challenger 1 claimed 300 kills against armoured vehicles for no losses. It also has the distinction of the longest tank-to-tank kill in military history, destroying an Iraqi tank at a range of 2.5 miles (4 km)

the downside of the challenger two is that it is slower then the A1 and leopard, but greatly heavy armoured then both.

leib10
10 Mar 06,, 15:42
Smoothbore also gives HEAT rounds more effectiveness because spinning them reduces their ability to penetrate more armor.

RustyBattleship
10 Mar 06,, 17:15
Smoothbore also gives HEAT rounds more effectiveness because spinning them reduces their ability to penetrate more armor.
Spinning keeps the projectile point first. Very important if you have a hardened tip to start punching through armor. Even fin stabilized projectiles "spin" by the pitch of the fins to keep pointy end forward.

Take a close look at the fletching of an arrow. You will notice the feathers are actually set slightly off centerline giving a pitch to "spin" the arrow. They are not drag stabilizers as most people think.

Which reminds me of Kotcher's silly Robin Hood movie. Their arrows did not rotate or "spin".

KPR
11 Mar 06,, 02:47
HEAT doesn't need kinetic energy to penetrate armor.

tankervet
11 Mar 06,, 03:02
HEAT doesn't need kinetic energy to penetrate armor.

Who said that HEAT rounds require kinetic energy to penetrate armor? Just curious not trying to start an argument.

But of course your right, HEAT uses a PIBD switch to detonate therefore no kinetic energy is needed.

RustyBattleship
11 Mar 06,, 04:32
Who said that HEAT rounds require kinetic energy to penetrate armor? Just curious not trying to start an argument.

But of course your right, HEAT uses a PIBD switch to detonate therefore no kinetic energy is needed.
But you STILL have to keep it nose forward for range, accuracy and stability to have the body in the right position on impact.

Otherwise that round is going to keyhole all the way down range and wander several minutes off in any direction. So whether you need kinetic energy or not, you still need to impart a slow spin on the projectile.

The only ordnance we fired from our M-41s and M-47s from my day that rifling was counterproductive was cannister rounds (later called beehive). The spin spread the pellets out to wide and too fast. That's when a smoothbore would be much more efficient and keep that clump of shot a little closer together.

Hmmm. I just realized my last statement gives more advantage of a smoothbore over rifled bore. It's a much better shotgun.

Bill
11 Mar 06,, 10:33
Rifeld bore gives greater distance and pentetration then smothe bore.!


You have that backwards.

Think about it.

Bill
11 Mar 06,, 10:37
Spinning keeps the projectile point first. Very important if you have a hardened tip to start punching through armor. Even fin stabilized projectiles "spin" by the pitch of the fins to keep pointy end forward.

Take a close look at the fletching of an arrow. You will notice the feathers are actually set slightly off centerline giving a pitch to "spin" the arrow. They are not drag stabilizers as most people think.

Which reminds me of Kotcher's silly Robin Hood movie. Their arrows did not rotate or "spin".

APFSDS actually rotates very, very little. What makes APFSDS type rounds so stable is thier excellent aspect ratio.

FFAR rockets do spin though, and to the best of my knowledge, so do arrows.

leib10
11 Mar 06,, 14:56
Yep, arrows spin. That's what fletching is for. :biggrin:

tankervet
11 Mar 06,, 15:59
But you STILL have to keep it nose forward for range, accuracy and stability to have the body in the right position on impact.

Otherwise that round is going to keyhole all the way down range and wander several minutes off in any direction. So whether you need kinetic energy or not, you still need to impart a slow spin on the projectile.

The only ordnance we fired from our M-41s and M-47s from my day that rifling was counterproductive was cannister rounds (later called beehive). The spin spread the pellets out to wide and too fast. That's when a smoothbore would be much more efficient and keep that clump of shot a little closer together.

Hmmm. I just realized my last statement gives more advantage of a smoothbore over rifled bore. It's a much better shotgun.

Hey Rusty, I agree with you. Spin and Kinetic energy are not one in itself. You and have one without the other, well kindof I guess.

My point being that a APFSDS round flying at say 100ms is not going to be very effective, due to no Kinetic Energy
But a HEAT round traveling at 100ms is going to be just as effective because of the way it detonates.

Bill
11 Mar 06,, 16:06
The lower the impact velocity, the more effective HEAT will be. OF course that has the drawback of causing your round to get downrange reaaaaaaaaaaaally slow(Dragon anyone?)

sappersgt
11 Mar 06,, 20:13
APFSDS actually rotates very, very little. What makes APFSDS type rounds so stable is thier excellent aspect ratio.

FFAR rockets do spin though, and to the best of my knowledge, so do arrows.
Is anyone still using HESH rounds? How effective would a HESH round be against soft / hard targets? I asked for them in a training exercise but never actually fired one (suprised the referee though!) . My thought at the time was to get off the first shot in a meeting engagement without having to change ammo types.

tankervet
11 Mar 06,, 20:41
Is anyone still using HESH rounds? How effective would a HESH round be against soft / hard targets? I asked for them in a training exercise but never actually fired one (suprised the referee though!) . My thought at the time was to get off the first shot in a meeting engagement without having to change ammo types.
From the best of my knowledge the Brits are the only ones still using the hesh rds.


This is a pretty good write up from tanknet


HESH design considerations – 1964

HESH ammunition (or HEP in US Army terminology) has always been somewhat mysterious, compared to conventional armour piercing ammunition, both because its performance is hard to quantify, and because it seems to get little publicity in comparison to other ammunition types. Here are some HESH design considerations, further summarized from an American 1964 overview reflecting the state of the art of HESH engineering at that time. Please bear in mind that HESH shells were still considered relatively new at that point, and some development was still to follow.

Function

HESH rounds work by bringing a charge of high explosive into intimate contact with an armour plate and detonating it. Shock waves then travel through the plate at right angles to the surface, reflect off the back of the plate, reinforce each other, and cause the steel to rupture (spall) at the rear if the explosive charge was powerful enough. The spall detached by the HESH round is typically in the shape of a disc that is slightly wider than the explosive contact area, and travels between approximately 30 m/s and 240 m/s, depending on the quality and thickness of the armour, and the amount and type of explosive.

Explosive

The preferred explosives are those with high detonating velocities, and the best results are obtained when the explosive can squash into the shape of a flat cone. To do this the explosive cannot be crumbly, but must have a soft putty-like consistency. Composition A-3 (91RDX-9Wax) proved the best, with Composition C-4 (91RDX-9Polyisobutylene binder) coming second. Cast explosives such as TNT or Composition B (39TNT-60RDX-1Wax) have the wrong properties, and do not provide a HESH effect. Unfortunately, Composition A-3 and C-4 need to be press-loaded, which is more time-consuming and expensive than casting the explosive.

Construction

HESH rounds need a very thin soft nose and thin walls, to allow the explosive to deform and come into proper contact with the armour plate. An annealed steel nose was found to work best, better even than softer copper, which was a surprise. The preferred nose shape was an ogive, which provided a greater contact area on impact than shorter hemispherical noses. Thinner nose material was found superior to thicker material, but this was limited by the need to withstand the pressures during the explosive’s press-loading process.

The thin walls are weak, and therefore difficult to launch at high velocity. They also cannot withstand the forces that are normally used to press on a driving band during manufacture, causing the designers to resort to welded overlay driving bands, which had previously been restricted to recoilless rifle rounds. The thin walls are also light, and thus have a low rotational moment of inertia, which makes the shell difficult to spin stabilize. This was overcome by the use of a blunt-nosed ogive shape, which drag stabilizes the projectile. However, the lightweight shell body and blunt high drag design mean the round has a poor ballistic coefficient, and slows down rapidly. Nonetheless, the shells were considered at least as accurate as HE shells of equivalent caliber.

Initial British HESH shells were of two-piece construction (nose cap and body), and the Americans copied this design, until they developed a one-piece shell body. This lowered production costs, and allowed an increase in muzzle velocity (presumably due to the removal of the weak joint).

Fuzing

Choosing proper fuzing delay is important for HESH rounds, because the explosive must have time to deform and squash against the armour before it is detonated. Optimal delay time is less for oblique impacts than it is for vertical impacts, and will obviously vary with impact velocity. (This is presumably part of the reason for narrow range of effective velocities.) However, the engineers admit “Beyond that, not much is known about HEP fuzing requirements.”

Performance

HESH rounds will generally defeat steel tank armour of about 1.2 calibers in thickness, between the angles of 0 and 60 degrees. Since the shockwave from a detonating HESH round is transmitted approximately at right angles to the armour plate’s surface, the increased line-of-sight thickness presented by angled armour is not a factor, and spalling can be accomplished where the LOS thickness is greater than 1.2 calibers. However, the efficiency of a HESH round is greatest when it strikes at right angles to the armor plate, and in oblique impacts it is not quite as effective, so angle cannot be entirely ignored.

The performance of HESH rounds depends on impact velocity, and there is a rather small range of velocities at which the rounds will function properly. HESH rounds need to impact between roughly 300 and 600 m/s to be effective. Rounds that are too fast will deflagrate prematurely (i.e., have a low order detonation) due to the force of the impact. (This seems to have been slightly mitigated by the use of an inert bitumen filler in the nose, which protected the explosive from the shock of impact. Thus the M393 HEP-T round has a muzzle velocity of 732 m/s.) Those that are too slow won’t come into proper contact with the armour. The minimum velocity requirement was seen as a serious handicap for lightweight low-velocity recoilless launchers. As of 1964, attempts were being made to widen the range of effective impact velocities by developing new fuzes.

The British were reported to have done “a considerable amount of firing” against spaced targets, and had found that skirting plates could render HESH rounds ineffective, by preventing the shockwave from reaching the main plate. They also found that a spaced armour configuration of a layer of sponge rubber between the outer plate and the main armour could render HESH shells ineffective. (This seems to contradict the reported penetration of a spaced Leopard 1 turret by HESH. Paul, could you maybe send me a copy of that photo, so I can post it up?)

One side effect of the extremely thin shell walls was that they were considered to provide a valuable secondary fragmentation effect against armoured vehicles, apparently because they would break up into many small high velocity fragments, unlike thicker walls, which would make fewer slower fragments. (I guess these would strip off external features, damage optics, etc., as well as being very effective against soft targets.)

Shadowsided
26 Mar 06,, 21:23
Smoothbore guns have greater velocity. they're btter for delivering more power. Simullacram that was an iraqi tank rifled guns arent as powerful as smoothbores they do less damage. may i ask a question.. does more velocity=more range???

Anyways if that was the case with rifled (more range and power) then why has every country abandoned it and moved on to smoothbore.

RustyBattleship
27 Mar 06,, 00:31
Smoothbore guns have greater velocity. they're btter for delivering more power. Simullacram that was an iraqi tank rifled guns arent as powerful as smoothbores they do less damage. may i ask a question.. does more velocity=more range???

Anyways if that was the case with rifled (more range and power) then why has every country abandoned it and moved on to smoothbore.

Maybe I'm a little old fashioned here. But when I was a tank gunner and years later part owner of a couple of gun shops we found a rifled barrel to give higher velocity thus greater penetration, also flatter trajectory thus more accuracy and finally the higher velocity (over a projectile of the same weight and caliber) gives more range. Nice for defilade fire when you don't have enough howitzers to go around.

The reason why a rifled bore (at least in MY day) gave higher velocity was because of the gas seal and the resistance the rifling imparted on the copper base ring. This resistance allowed more of the propellent to burn before the projectile left the muzzle. Also, on the M-41 tanks we had in my battalion, we noticed a strange thing when we were running the bore cleaning brush through. The rifling near the muzzle turned a hair sharper than down the rest of the tube. This was colliquially called "snap turn" rifling to allow even more resistance and more assurance of ALL of the propellant igniting before the round exited the muzzle.

There were also some guns (they were German 88s or American attempts to copy the 88 with the 90mm) that actually had a very slight choke even though they were rifled. This choke, or slightly reducing the diameter of the barrel as with a shotgun, was also intended to build up pressure for the highest possible velocity to cause ALL of the propellent to be burned while the round was still in the barrel (but very close to the muzzle).

Whether modern smoothbore guns use a choke to increase pressure or not I do not know (been out of the tank business for a while and the Army is a little hesitant about a guy crowding 70 to play around with their latest toys).

But if a smoothbore is NOT choked, you would need a very special propellent to keep building up pressure as the round skids down the tube.

As a final jog in the memory cells, I do recall our turret mechanic Instructor at Fort Irwin (back in the early 60s) saying that experiments were still being conducted with various types of rifled barrels and even smoothbore guns but not to worry as they would be designed to be interchangable with the receivers we already had. And I have a bridge in Brooklyn for sale too.

It was still several years before I got involved with a smoothbore gun and that was the 8" Major Caliber Gun we installed on the USS Hull. It was to be the test gun for future installations on ALL Spruance Class Destroyers and Ticonderoga Class AEGIS Cruisers. But Senator Proxmire of Wisconsin (I am ashamed to admit he was from my home state) got the gun system totally cancelled calling it "The most innaccurate gun in the Navy".

Yeah. She blew the hull of the old USS Cunningham in two with one shot at over 10,000 yards.

Shadowsided
27 Mar 06,, 01:25
Maybe I'm a little old fashioned here. But when I was a tank gunner and years later part owner of a couple of gun shops we found a rifled barrel to give higher velocity thus greater penetration, also flatter trajectory thus more accuracy and finally the higher velocity (over a projectile of the same weight and caliber) gives more range. Nice for defilade fire when you don't have enough howitzers to go around.

The reason why a rifled bore (at least in MY day) gave higher velocity was because of the gas seal and the resistance the rifling imparted on the copper base ring. This resistance allowed more of the propellent to burn before the projectile left the muzzle. Also, on the M-41 tanks we had in my battalion, we noticed a strange thing when we were running the bore cleaning brush through. The rifling near the muzzle turned a hair sharper than down the rest of the tube. This was colliquially called "snap turn" rifling to allow even more resistance and more assurance of ALL of the propellant igniting before the round exited the muzzle.

There were also some guns (they were German 88s or American attempts to copy the 88 with the 90mm) that actually had a very slight choke even though they were rifled. This choke, or slightly reducing the diameter of the barrel as with a shotgun, was also intended to build up pressure for the highest possible velocity to cause ALL of the propellent to be burned while the round was still in the barrel (but very close to the muzzle).

Whether modern smoothbore guns use a choke to increase pressure or not I do not know (been out of the tank business for a while and the Army is a little hesitant about a guy crowding 70 to play around with their latest toys).

But if a smoothbore is NOT choked, you would need a very special propellent to keep building up pressure as the round skids down the tube.

As a final jog in the memory cells, I do recall our turret mechanic Instructor at Fort Irwin (back in the early 60s) saying that experiments were still being conducted with various types of rifled barrels and even smoothbore guns but not to worry as they would be designed to be interchangable with the receivers we already had. And I have a bridge in Brooklyn for sale too.

It was still several years before I got involved with a smoothbore gun and that was the 8" Major Caliber Gun we installed on the USS Hull. It was to be the test gun for future installations on ALL Spruance Class Destroyers and Ticonderoga Class AEGIS Cruisers. But Senator Proxmire of Wisconsin (I am ashamed to admit he was from my home state) got the gun system totally cancelled calling it "The most innaccurate gun in the Navy".

Yeah. She blew the hull of the old USS Cunningham in two with one shot at over 10,000 yards.
http://people.howstuffworks.com/m1-tank3.htm

here u go review this . The one with the huge Abrms tank gun. Besides that was the old days times have changed. Tr u they dont stabilize rounds as well but fire at hiher velocites and fins can be used for stabilization so rifling is not required.

RustyBattleship
27 Mar 06,, 02:09
http://people.howstuffworks.com/m1-tank3.htm

here u go review this . The one with the huge Abrms tank gun. Besides that was the old days times have changed. Tr u they dont stabilize rounds as well but fire at hiher velocites and fins can be used for stabilization so rifling is not required.
Thank you VERY much. Though I'm an old codger I still like to keep learning.

Haven't figured out women yet though.

Officer of Engineers
27 Mar 06,, 03:07
Thank you VERY much. Though I'm an old codger I still like to keep learning.

*** ROLLING MY EYES *** Moma's boy doesn't take a hint, does he?


Haven't figured out women yet though.

Haven't figured them out but figured a way to live with them. Just smile and nod your head. Just smile and nod your head.

lemontree
27 Mar 06,, 10:52
Haven't figured them out but figured a way to live with them. Just smile and nod your head. Just smile and nod your head.
This means I'm on the right track. I just nod and say yes to every thing?... :)

Blademaster
28 Mar 06,, 08:14
This means I'm on the right track. I just nod and say yes to every thing?... :)

Well for starters, it means one thing, you will be saying yes to every inane and asinine requests for errands and jobs. One of these days, you will severely regret saying, "Yes". My friend, you gotta learn how to say "NO!".

Oh by the way, make sure you get a nice comfy couch and a blow up doll since you won't be getting some pvssy for a while. :biggrin:

lemontree
28 Mar 06,, 12:02
Well for starters, it means one thing, you will be saying yes to every inane and asinine requests for errands and jobs. One of these days, you will severely regret saying, "Yes". My friend, you gotta learn how to say "NO!".

What makes you think that I follow up on the 'yes'?...I say yes make her happy and then do things my way.

Oh by the way, make sure you get a nice comfy couch and a blow up doll since you won't be getting some pvssy for a while. :biggrin:
For for? :confused:

Blademaster
28 Mar 06,, 14:51
For for? :confused:


Errr... ummm.. You will figure out when you see the doll. ;)

RustyBattleship
28 Mar 06,, 20:34
How did this great thread on smoothbore guns vs. rifled bore guns degenerate into misfires?

Shadowsided
29 Mar 06,, 03:13
Cut it out people lets get back to the topic (smoothbore vs rifled) omg sometimes i swear some of u ppl r so god damn immature n mean leave rusty battleship alone you dont have to harass the poor guy. geez he's a little old he nneds to get back on track in military aviation! :mad:

Officer of Engineers
29 Mar 06,, 03:21
We're not picking on him, you freaking illiterate. We're picking on you.

Bill
29 Mar 06,, 20:10
LOL, one post one kill Sir. :)

lemontree
30 Mar 06,, 08:05
How did this great thread on smoothbore guns vs. rifled bore guns degenerate into misfires?
Sorry about that sir but some youngsters have not learnt the art of seduction ;) (BM unfortunately has used a doll :eek: ).

We may get back to discussing the topic at hand. I am sure you will agree that a little jest during the briefing always helped lighten up things.

Shadowsided
03 Apr 06,, 18:46
you peopel must be in fifth grade and being immature out of all forums ive been to you guys have been making the most childish comments and not adressing the issue pikcing on people.

Officer of Engineers
03 Apr 06,, 18:59
LMAO!!!!

Your terrible grammar and horrendous spelling and you call us in the 5th grade?

Blademaster
03 Apr 06,, 23:37
(BM unfortunately has used a doll :eek: ).



What made you think that I used a doll. I don't need a doll. I am single and blissfully not married. :biggrin:

lemontree
04 Apr 06,, 05:52
What made you think that I used a doll. I don't need a doll. I am single and blissfully not married. :biggrin:
Just nitpicking.... :biggrin: I know what that bloody doll is about.

Triple C
13 Apr 06,, 18:14
Rifled gun can accomodate a greater variety of shells. Shells like HE-Frag and beehive are very useful against the infantry. M1A1 for the better part of the past three decades got only HEAT and APFSDS.

That said, it's not impossible to get those shells for smooth bores--the Americans just got a smooth bore beehive round, and the Ruskies had 125mm HE-Frag for years.

Bill
13 Apr 06,, 19:38
you peopel must be in fifth grade and being immature out of all forums ive been to you guys have been making the most childish comments and not adressing the issue pikcing on people.

Your grammar sucks to the point as to make your posts unintelligible.

Please seek professional education assistance.

tankervet
13 Apr 06,, 22:05
Rifled gun can accomodate a greater variety of shells. Shells like HE-Frag and beehive are very useful against the infantry. M1A1 for the better part of the past three decades got only HEAT and APFSDS.

That said, it's not impossible to get those shells for smooth bores--the Americans just got a smooth bore beehive round, and the Ruskies had 125mm HE-Frag for years.

Not a beehive but a canister. They are close but not the same thing.

Bill
14 Apr 06,, 02:11
Not a beehive but a canister. They are close but not the same thing.

Flecthette vs grapeshot, yes?

tankervet
14 Apr 06,, 02:35
Flecthette vs grapeshot, yes?
Yeah thats correct. I have no experience with the beehive but from what I have seen of the canister its very impressive.

Also there is no reason why a smoothbore tank could not fire a antipersonel round such as a beehive or whatever. Obviously because we have it now but even before if you think about it. Most antipersonel rounds dont require stabilization in air and thats the only disadvantage of smoothbore is that rounds must be fin stabilized.

Nagalfar
14 Apr 06,, 16:02
Yep, arrows spin. That's what fletching is for. :biggrin:

There are several ways to set the fletching on arrows.. the are set in various offsets, that are measured in degrees, 8, 10 and so on, not all arrows have a fletching offset, some fletchings are set to zero, NO SPIN on the arrow, the aerodynamic drag of the fletchings is what keeps a arrow straight during flight, some people shoot better without spin other shoot better with it.. spin has little to do arrow being accurate..

Smooth bore Vs. Rifled, Smooth Bore allows for higher velocities, adding to range and penetration at greater distances due to greater kinetic energy down range (weight X velocity = Kinetic Energy), adding to the ability to punch though amour at greater distances.. the loss of accuracy is extremely minimal, to the point of not being a consideration when the object being fired is provided with the proper aerodynamics to maintain a constant drag coefficient in flight to maintain its stability..

Spinning has nothing to due with keeping the nose pointing in the right direction, it has to due with accuracy.. proof of this being, if you take a cross section of a bullet, and find the center of mass, the center of mass is usually well behind the actual measured center for most all bullets and shells (arty). Yet, when a bullet strikes something like soft to moderate tissue almost all bullets turn heavy end first, meaning, when a bullet strikes, on average, most will go anywhere from 4" to 19" (depending on caliber, type of bullet, and energy of bullet and medium bullet is moving though) before they turn end for end and continue, when they exit a body it is more often tail first (basic physics, heavy objects pull light objects unless acted upon by other forces).

RustyBattleship
15 Apr 06,, 03:10
Well, I've done a lot of pit time and pasted enough targets to know when a hobbyist has sized down his bullets too small for the rifling of his barrel. I'm sure you know what the term "keyhole" means.

Actually, ballistics are very complex. Whether smooth bore or rifled, if the projectile is any shape other than spherical it has to be designed to keep the center of (air) pressure forward with the center of gravity aft. Accuracy of that theorum was discovered accidentally when certain hollow point bullets proved to be more accurate than standard FMJ.

If you have any National Match rounds for 7.62 NATO (M-1A & M-14 rifles) or .30-06 (M-1 Garands & 03-A3 Springfields) lying around, take a close look at the nose of the bullet. It has a very small hole in the tip. This is to build up forward air pressure.

Oh! As for arrow fletching. Almost all arrows fletched for speed, accuracy and/or penetration are canted for spin. The fletching is usually relatively small also, particularly for high speed arrows. But fletching for distance shooting is rather large and usually not canted and are called "Flight" arrows.

A friend of mine (Bill) used to participate in distance shooting. He cheated though. Weight lifting was a hobby of his. Plus he was a Structural Steel worker with me (adding versatility to his weight trained muscles). Plus the bow was custom built by one of our fellow workers (a welder at that) and to shoot it Bill had to lie on his back and use both hands AND both feet to draw it.

Not too many archery ranges around that are long enough for that kind of contest.