What is the performance of the "silver bullet" 120 mm rounds used on the Abrams M1A1 and A2 tanks?

A. The actual armor defeating capabilities of the M829 APFSDS-T (Armor Piercing Fin Stabilized Discarding Sabot-Tracer) 120mm rounds as fired by the M1 Abrams tank are classified and have never been released. However, they will reportedly kill any known main battle tank in the world with one shot. The original M829 threw a 9.41 pound (that's 65,870 grains), 1.06" diameter, 24" long, depleted uranium "dart" at 5480 f/s! The A1 version fired a 10.78 pound dart at 5170 f/s and the current A2 version throws a slightly longer (30") but skinnier (.8") 10.85 pound dart at 5512 f/s. Operating pressures of the M829 series are between 74K psi and 96K psi depending on the particular variant. Muzzle velocity is within � 78 m/s (256 f/s) between 0 and 120 degrees F (-18 to 49 degrees C). The nose of the "darts" is protected by a ballistic wind screen and the tip shape varies, being chisel shaped for the A2 version.

The "effective" range is listed as 3000 meters (limited mainly by group size) but one round killing hits have been obtained at close to 6000 meters and reported accuracy is sub minute of angle. The extreme range of the M829A2 is close to 70 miles when fired at 55 degrees elevation. The depleted uranium "dart" uses its 4 million plus foot pound of energy to literally burn its way through armor. The thermal flux at the point of impact is estimated at 1 million degrees. The DU is pyrophoric, that is, self incendiary and will ignite anything within the target as well as producing a lethal barrage of fragments from its penetration. There is also an M829E3 (A3) round under development that should have even more spectacular ballistics than the previous rounds.

Because of the M829's extreme maximum range a shorter ranged practice round, the M865, was developed. The M865 TPCSDS-T (Target Practice Cone Stabilized Discarding Sabot with Tracer) training round throws a 7.05 pound aluminum dart at 5577 f/s. (This round has very close to the same trajectory out to 2000 meters or so but a MUCH shorter maximum range than the M829 and can thus be safely fired on most tank ranges.) However, within its range it can still kill many armored vehicles quite handily and will reportedly go entirely through the older US M48 tank at 1200 meters.

Impressive rounds, eh?

"Tell them Valdez is comming"

Sounds like a perfectly adequate deer round, don't you think?

I have a buddy that is an Abrams Tank Commander. When he first told me the think produced velocities in excess of 5000 fps I thought he was nuts. He said the round will hit a tank with so much energy the effect fo the people in the tank is pretty gruesome!

Hmmm...wonder if that could be chambered in the TC Encore? Off to the shop!!!!!!

SHIT

Hmmmmmm
You wouldn't happen to know the BC for this round? I'm thinking this would a great groundhog round as well as prairie dog round for windy days.
Which Ford pickup has the capacity, in the bed, for mounting this gun?
Jim

"In the 1991 Gulf War, The Abrams proved itself the best tank in the world, knocking out Iraqi T-72s with impunity - no Abrams were destroyed by enemy fire"

This according to "Armored Fighting Vehicles" by Philip Trewhitt Copywright 1999.

[ 04-01-2003, 18:19: Message edited by: Curtis_Lemay ]

Yeah, pretty impressive, but just think what it could do with Sierra Matchkings...

I've a question.. for anyone who might know... in referance to these rounds, and the rounds that the Abrams fire... I know how the rounds mentioned work for anti-tank, anti-vehicle use... but do they have "traditional" HE rounds?
Say for use against buildings or bunkers or what have you?

Yes, they do fire HE but IIRC it's a multi-purpose HEAT (shaped-charge) round.

If you are thinking of taking this gun hunting, you need to be careful where you point it. If fired at an upwards angle of 55 degrees, the APFSDS will travel something like 70-80 miles before it touches down....

Tony Williams: Military gun and ammunition website and Discussion forum

The max range of this round is what amazes me! It's almost the same as the Paris Gun of WWI!!

I'm old.
The ballistics I remember, ala 1983 for a 105mm cannon:

37 pound HE round at 2800 fps, max range 27 miles
(guy pointed one up max, hit an outhouse at 27 miles at Hunter Ligit).

29 pound, 3700 fps sabots, with tracers, would go through a tank, at 10 miles, hit the hill, and bounce for another 5-7 miles.
Beautiful at dusk, or night.

I can safely say that the HE rounds are deadly on ground squirels, and I did manage to heart shoot
one at 10 miles with the 105mm.



God Bless our guys, and hope our technology can save em from those nuts...
s

"As far as groundhogs go, if you just graze them, the backwash should suck the air from their lungs and they would suffocate. Saves the meat, but it is tough on backstops."

I read a news report 3 days ago about US tank crews doing just what you mentioned, except the "varmints" were Iraqi soldiers shooting from doorways lining a street. Two M1's fired directly down the street, and the vacuum created by the passing rounds actually SUCKED the Iraqi soldiers right out of the buildings and into the sights of the Marines. Damn. I just had a mental image of firing one over a p-dog colony and seeing 100 p-dogs going airborne :-)

May need a VA muzzle brake.
Recoil for the first mentioned 1.06" round is
4,393,440 foot pounds...



Guess it wasn't just an illusion that made it look like the tanks moved backwards under recoil...
s

More info and diagrams...

DOD website

[QUOTE]Originally posted by Tony Williams:
[QB]Yes, they do fire HE but IIRC it's a multi-purpose HEAT (shaped-charge) round.

For interests sake the Challenger 2 (the British MBT) has a 120mm rifled gun using APFSDS but the HE round is HESH (high explosive squash head) which is not a shaped charge. This is very effective producing a 'scab' of metal on the inside of the hit tank that wizzes round inside - not nice. No shaped charge as these do not like the spin induced by the rifled barrel. From a dim and distant memory the APFSDS has the spin reduced with the sabot in effect having bearings.

How is IIRC stabilised?

Wow. What a cool post. I'm an M1A1 Abrams tanker and I just got back from gunnery. It was my first time as a gunner.

Some of the stuff in this thread may be exaggerated. I don't know the extreme range of a Sabot round, but I would take the 70mile+/- figure with a grain of salt.

No soldiers were sucked out of their fighting positions by the vacuum of a round going down the street. However...... on the range I had an engagement that was Tank/Troops/Tank. For the troop engagement I forgot to index Coaxial Machinegun and fired a Sabot at a man-size pop-up silhouette. I got him in the face and I was told that I knocked down his 3 buddies.

The trajectory of the Sabot round is so flat that I hit all my targets, from several hundred meters to over 2000meters, without using the Laser Range Finder. We didn't have an LRF failure, I just forgot to arm it

It was kinda funny and embarrassing too. Through it all, I did manage to qualify so I came away happy. I'll try to get a pic of the troop target with a sabot to the face.

The thing that most amazes me is that they get that kind of accuracy from a smoothe bore. Could you give us some insight into that?

We've been discussing this same topic on another site. There is an excellent pic of one in flight, losing it's sabot. I tried to post the pic here but I can't get it to work. If you want to see it, go here:

http://www.excaliburcrossbow.com/phpBB2/viewtopic.php?t=1292

I have been told that the modern tank rounds work likt this:

They impact the enemy tank, and the heat transmissionis so high that they MELT their way through the enemy tanks armour.

The enemy tanks armour fragments, blowing all sorts of nasty bits through the crew.

The air pressure change is so extreme that it pops the turret off the enemy tank.

That's why you see so many blown out tanks missing their turrets.

Any comments from those that KNOW?

Gatehouse-
The reason the turrets pop off T-72s/T-80s (as far as I know, the only tanks knocked out in combat by the M1) pop off is the powder from the main gun rounds igniting. Those tanks have an autoloader. The rounds are in two pieces; powder bag and projectile. The powder is stored in a ring around the turret. If a Sabot passes through the powder it will ignite and set off a chain reaction. If the chain reaction is fast enough, the turret goes skyward. If the chain reaction is not that fast, it still must be an inferno that the crew cannot survive. If the powder is not hit, the projectile and metal fragments passing through will likely kill or injure the crew. Don't forget fragments from anything struck inside that tank as the round passes through.

By comparison, the M1 uses 1-piece rounds stored in a "honeycomb" rack at the rear of the turret. There is a sliding door operated by a knee switch, therefore the only time the crew shares space with the main gun rounds is when the loader is grabbing one. Above these ammo racks are blow-off panels. If a round ignites the M1's ammo, the explosion will take the path of least resistance and go through the roof of the turret. I once saw a video on Discovery Channel demonstrating this. A camera was inside the turret showing the ammo door bowing a bit, but it did not fail.

El Viejo-
Something I though of after posting last night is that the fire control computer also contributes to accuracy. Just some of the variables used by the computer: Cant angle of the tank, wind speed (at the tank*), ammo lot #, ammo temp, air temp, barometric pressure, etc, etc, etc.

Why take a wind speed reading at the tank? Well, it's kinda hard to take one midway to the target in combat and if a round is blown off course at the muzzle, it will be off course for its entire trajectory.

I saw a diagram of a AP shell for the Abrams. It indicated that there was some kind of 'rocket' engine in the shell. Can anyone comment on this?

Also, I saw a video of a tank firing. There was a lot of smoke, which makes me question what kind of powder they are using. I have been told that the large naval guns use black powder. Do tanks do the same? What kind of chamber pressure does the tank round create?

I am not sure what a coaxial machine gun is? Could someone explain the difference between that and an ordinary machine gun?
I think it was very considerate of the Soviets to put a ring of explosives around their turrets

BTW, what is the latest Russian tank?

[ 04-13-2003, 05:51: Message edited by: El Viejo ]

I am not aware of any AP round for the Abrams. At this time we have Sabot, HEAT, and MPAT. None have rocket assist. (I believe some artillery shells do) The MPAT can be used for air or ground targets. In Air mode it uses a proximity fuze. In Ground mode it uses an impact fuze. The tip of the round actually rotates between either setting.

The HEAT or MPAT could certainly be used against personnel. Kinda messy, I suppose, but if I'm out of 7.62 or .50cal and some SOB has an anti-tank weapon, he's getting a main gun round.

I have never seen the propellent inside a main gun round. I have been told it looks like small grey pellets of dog food (small for dog food. much larger than regular gun powder). I don't have anything in writing at my house, but I believe the practice Sabot round holds 36 pounds of propellant.

They do not use black powder. What appeared to be smoke was most likely dust kicked up by the muzzle blast. At areas where tanks train, they crush the gravel and dirt until it is as fine as talcum powder. I've seen dust hang in the air for 30 minutes when there is no wind.

I can't answer the chamber pressure question but it was addressed in a reloading manual published by A-Square. It's the one with a tank firing on the cover. Maybe someone on the Big-Bore message board who has the manual would be kind enough to answer that for you.

A Coax machinegun is one aimed co-axially with the main gun. It uses the same optics but with the flip of a switch it can fire a 7.62mm machinegun. Look at a pic of an M1 from the right side. The short tube beside the main gun is the coax "smoke tube"(I have no idea how it got that nickname) Something really cool about that; If you're the loader on a night-time range and you lean way over to see the end of the smoke tube, the muzzle blast looks like a mushroom cloud. It's bad-ass.

The latest Russian tank is the T-90. It looks very similar to the T-72 and T-80.

Here's a pic for ya: I shot this at the Range 117 Calibration Complex at Grafenwoehr, Germany in January '99. I was in my loader's hatch next to the firing tank. I used a Canon T-90 with a shutter speed of 1/4000sec and the motor drive. I don't remember the exposure setting, but the photo was shot at noon on a cloudy day. It took 180 frames of film to get this one pic and it was still just dumb luck that I caught it.



BTW- The white circle on the ground is the shock wave. It blows my mind that I caught it. A lot people thing the trail of fire leaving the blast is the round, but I was not that fortunate. I believe it is simply some of the fireball getting sucked along by the round.

[ 04-13-2003, 07:16: Message edited by: LongDistanceOperator ]

Here's another pic. I snapped this in July 2000. For this one I used a cable release, which was my normal setup for tank firing pics. I monitored the radio from the tank and when the gunner was about to fire, I opened the shutter and held it for a second or so.

This is my Battalion Commander getting a one-shot hit on a 2,000meter mover.

The round appears to tumble at the end of its trajectory but that is actually the shock wave shaking the camera towards the end of the exposure.

Great pictures.
By AP, I ment Sabot. I was unsure of the nomenclature.

Have you got any pictures of the target?

I know, old thread, but I have a couple of anecdotes to add, here. One of the by-products of shooting the "Silver Bullet" is that with repeated exposure to firing, the sound waves propagated by the gun firing can cause, ahem, "temporary degradation of certain 'soft' tissues" Yep, you can get the runs from being exposed to to much firing. Secondly, my platoon sergeant, David Ayers, was hit twice by the 125 mm gun of a T72 at around 900 yds on the left front turret glacis. His wing-man had to tell him he was being fired on, SFC Ayers never even knew he was being shot at. (Damn Good Armor, that!) His wingman then shot at the T72, which was dug in, striking the berm in front of the T72, passing approximately 30 feet through the berm, through the front hull of the tank, through the turret, engine and exited the rear of the tank, and buried itself deep within the earth behind the T72.

The moral? Don't bring a T72 to an M1 fight.

It might have been old 120 but I had never seen it. I enjoyed the dialog and the pics. Thank you. derf

Like MBTs ?

the 120 mm smoothbore barrel is the same ( Rheinmetall ) the round and all stuff around the barrel is different.

http://kovy.free.fr/video/leclerc_384kbps.wmv

http://perso.wanadoo.fr/koriwenn/datas/videos/PRESEN~1.MPG

http://www.defense.gouv.fr/visites_virtuelles/char_leclerc/indexjava.htm

http://perso.wanadoo.fr/pro.site/leclerc
( above URL , 10 days only )

this MBT is the only one until today to have hit the NATO target at 3000 meters distance on the move at 35 mph

Enjoy !

[ 06-09-2003, 15:36: Message edited by: Edmond ]

Nice varmit gun!

HAHAHAHAHAHAHA !

Hey Edmond,

1. Don't you guys have any real mountains to try the tank out on rather than just using dirt piles in a flat field?

2. Don't you have any politicians who will allow the tank to be tried out in a live fire environment?

[ 06-09-2003, 15:56: Message edited by: 500grains ]

Combine all this with Bio. protection for the crew and you got one awesome mobile A.A.K.
(American Arse Kicker)