Coax Machineguns on Armor?


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BerettaNut92
March 19, 2003, 10:15 PM
What's the point of coax machine gun on something like an Abrams or Bradley? If there's a machine gun or two up top, why not use those? I know nothing about land warfare so pardon my ignorance :o

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Tommy Gunn
March 19, 2003, 10:19 PM
A tank commander will be able to fire at someone using a wire guided AT missle.

Andrew Wyatt
March 19, 2003, 10:25 PM
The coax MG is for targets that the main gun happens to be pointing at that aren't really suitable for the main gun.

Wire guided missile teams, infantry, trucks and other light vehicles fall under this classification.


the french don't use .30 cal coax guns. they use 20 and 25mm cannon. i think this is one of the few things the french do that's better than what the US does.

Redlg155
March 19, 2003, 10:46 PM
They are good for light armored stuff and wheeled vehicles. Of course the ultimate coax MG would be the Vulcan system. :D

Good Shooting
Red

Blackhawk
March 19, 2003, 11:15 PM
Think of them as being like a sidearm for an infantryman. They're used for quickly engaging close surprise targets like infantry or small utility vehicles.

I think 7.62 mm is the perfect round for them: very rapid fire, easily manipulated, and easy to handle ammo that can be carried in abundance as well as resupplied from infantry units.

beemerb
March 19, 2003, 11:23 PM
Infantry are killers of tanks.With explosives they can disable a tank or even knock it out.Or if they have antitank weapons the same is true.The coax is the defense against enemy infantry.In armored cav units the american infantry is suposed to defend the tanks but many times the infantry either gets wiped out or can't keep up.
Bob

dude
March 19, 2003, 11:33 PM
the coax is there because it is deadly

synoptic
March 20, 2003, 03:18 AM
If there's a machine gun or two up top, why not use those?

They require sticking your head out of the tank - not always the best place to be

Detritus
March 20, 2003, 04:01 AM
ultimate coax MG would be the Vulcan system.


has some one ben reading too much David Drake?? :D :D

Kharn
March 20, 2003, 07:08 AM
The Abrams carries ~42 rounds for the main gun, ~1000 rounds for the commander's M2 .50, and ~10,800 rounds for the loader and coax M240s.

One of the IDF's innovations was to replace the barrel-mounted searchlight on some of their tanks with an M2 .50. The ballistic computer was altered to include data for the .50, and has been used very effectively as a long range anti-sniper weapon.

Crunchies beware.

Kharn

ajacobs
March 20, 2003, 08:27 AM
The bradley only has a coax, no gun up top.

Billy Sparks
March 20, 2003, 08:50 AM
Matter of fact didn't the Germans in WWII field a heavy tank without a MG's? I seem to remember reading something about that. As I remember they quickly learned that was a mistake with Russian infantry taking out those tanks.

Oleg Volk
March 20, 2003, 09:57 AM
To clarify the question: is coaxial MG fixed to point the same way as the main gun or can it be articulated a little up/down/sideways?

synoptic
March 20, 2003, 10:01 AM
http://www.battletanks.com/images/M1_Abrams-2.jpg

coax is fixed to the same area as the main gun...it is always pointing where the main gun does

Oleg Volk
March 20, 2003, 10:04 AM
Wouldn't it be pretty slow to point? Maybe better protection of a fixed mount is preferred to the speed of flexible mount?

Intune
March 20, 2003, 11:05 AM
Oleg, it is real fast and smooth to get onto target. It is a lot easier to engage troops with than say, an M60. Very stable platform, optics, no recoil, muzzle flash, it really is much like a video game. There are times when you REALLY don't want to stick your head out of the hatch. When the enemy is present is one of those times.

Echo23TC
March 20, 2003, 12:12 PM
The coax is the preferred method of engaging machine gun targets. The turret spins 360 in six seconds, and with the laser and optics, picking out an individual target and hitting it at 5-600 meters is not a problem. The computer automatically compensates for crosswind, range, cant, speed and whatever else can affect trajectory. Just put the crosshair on the target, say, "On the WAY!" and pull the triggers.

The loader's 240 is in a totally free mount, very rudimentary sights, not much good for anything other than area fire.

On an M1A1 (what I ride), the TC's weapon is fired from inside the turret, with an ok sight system - I can hit a vehicle pretty easily, if everything works right. M1A2's lost the capability of firing the .50 from inside, when all the computers took that area.

Damn. I just got put on alert.

Anyway, if you've got any other questions about my baby, just ask. I'll answer them as long as I can!

Oleg Volk
March 20, 2003, 12:15 PM
Why doesn't 120mm have a muzzle brake? Earier guns did...

What's the minimum safe area from muzzle blast for infantry which follows the tank?

What's the max off-road speed at which suspension can keep crew members safe?

Echo23TC
March 20, 2003, 12:38 PM
Oleg, them's some good questions.

1. Muzzle Brakes are usually used on artillery tubes. I dunno why they haven't been on tanks recently, but you're right, the old M-48's had them. With the M-60 and the British 105mm though, they went away. Ask the British and German gun designers why they didn't find them necessary.

2. If you're infantry, you don't want to be in front of me when I fire. Sabot petals go out about 200 meters or more before they hit the ground - and they leave the tube at 5280 fps and weigh a pound or better. It will definitely ruin your day to get hit by one.

3. Depends on how rough the terrain is. I've been in spots where 30 or better is no problem. I've also been in places where 5 mph is it. Taking a tank into the air is sometimes fun. Most of the time, it hurts. Not the air part, the landing. There's nothing soft inside a tank - except the crew. And two of them are standing up, which is not the most stable position to be in.

MicroBalrog
March 20, 2003, 01:35 PM
Actually, doesn't the Russian BMP-3 have a:
1)100mm cannon/ATGW launcher +
2)30mm coax cannon + a
3)7.62mm coax machinegun +
4)3-4 7.62mm mounted machineguns +
5) 8 ambrasures built to allow 360 degrees fire suppression?

So they use BOTH a 30mm coax cannon AND a coax machinegun!
Probably the two are for different targets, but I don't know any more right now.

Echo23TC
March 20, 2003, 01:52 PM
Now that I think of it, I read once that the 25mm gun that the Bradley has was intended to be the coax in the original M1. I have no idea where they would have found room for the breech and ammo. Would have been neat, though.

Quartus
March 20, 2003, 02:00 PM
Hey, Echo! Thanks for your service! http://www.thehighroad.org/images/icons/icon14.gif


I think 7.62 mm is the perfect round for them: very rapid fire, easily manipulated, and easy to handle ammo that can be carried in abundance as well as resupplied from infantry units.

Yup. More is better. In this case, considering the intended use, more ammo is better.

they leave the tube at 5280 fps and weigh a pound or better

:what: Whoa! That could give a fella a headache! Good thing the grunts have Kevlar helmets!



:D

Sean Smith
March 20, 2003, 02:10 PM
Read about the M1A2 SEP here:

http://www.fas.org/man/dod-101/sys/land/m1.htm

Why a coaxial machine gun?

1. It gives 3 out of 4 crew members their own machine gun (gunner, commander, loader).
2. You don't have to get out of the tank to shoot it.
3. Because it is inside the tank, you can use internal storage space to hold a huge pile of ammo for it. External machine guns are limited to the ammo boxes on the guns themselves.
4. It is an extremely stable platform for shooting, and the gunner can use his thermal sights/ magnifying optics with the coax.

One thing to point out is that a M1's gun turrent can spin REALLY fast... it isn't like in WWII movies where the thing kind of clanks around.

Oleg Volk
March 20, 2003, 02:14 PM
Tamara pointed out that KV2 turret with 152mm howitzer couldn't even turn unless the tank was on level ground. Yet another case of measurements being an incomplete measure of quality of the design...same could be said about comparisons with newer designs like T72 and T90.

Sean Smith
March 20, 2003, 02:23 PM
I don't quite understand what you are getting at, Oleg. :confused:

Russian tanks suck? We already knew that. :D

mons meg
March 20, 2003, 02:31 PM
1. Muzzle Brakes are usually used on artillery tubes. I dunno why they haven't been on tanks recently, but you're right, the old M-48's had them. With the M-60 and the British 105mm though, they went away. Ask the British and German gun designers why they didn't find them necessary.

Keep in mind that the M198 155mm howitzer itself only weighs about 8 tons, while the 120mm gun on the M1 has over 60 tons to soak up recoil. The 155mm also has a lot more oomph.

Another thought, even with all that energy at the muzzle as long as you are behind the gun you are safe from blast. I mean, otherwise the gun crews would have to run away and use a loooong lanyard. ;)

MicroBalrog
March 20, 2003, 02:33 PM
What about the T-80?:D

Navy joe
March 20, 2003, 03:34 PM
Coax is definitely a good deal. As pointed out, the gunner has the main gun's laser rangefinder and computer at his disposal for the coax so some really nice shots can be achieved. In a target rich enviroment :D the gunner can stay busy with the coax while the TC scans for good targets while engaging light ones with his .50.

Been awhile since I've been around armor, brother in law was a M1 crew in the days of two Germanys. I was perusing my Janes Second Edition Armored Vehicles of the world and noted something odd. In the performance specs under road speed, I only saw one with a forward and reverse speed noted... the AMX-30 fielded by guess who?

Justin
March 20, 2003, 03:45 PM
IIRC, the AMX 30 is French.

http://www.battletanks.com/images/M1_Abrams-2.jpg That looks like the M1 Abrams on display at the Ft. Knox Patton Museum. One of the early ones that has the 105mm rifled barrel.

Very cool museum to visit!:cool:

Quartus
March 20, 2003, 04:09 PM
the AMX-30 fielded by guess who?


It was indeed the French, Justin. An interesting abomination it was, too!

Sort of to armor what the Manlicher Carcano was to sniper rifles, or the Reising to submachine guns.


Or Algore to politics! :D

Navy joe
March 20, 2003, 04:52 PM
I'm sorry, I said AMX-30, I meant GIAT Leclerc. 71km/hr fwd., 38km/hr reverse. Implied French joke still stands.

Quartus, thinking of the AMX-13 perhaps? That was/is that ridiculous two part turret autoloading contraption thing. The AMX-30 is reasonably conventional, I would say it is a good second line tank comparable to a T-72 or M-60. The Leclerc appears to be their idea for an M-1 comparable MBT. Autoloaders on tanks. Arrgh! They slow down loading and you have one less person to fix/fight when the tank is broke/stuck/out of fuel whatever.

T.Stahl
March 20, 2003, 07:00 PM
I heard that muzzle brakes had to go with the advent of sabotted KE rounds. Probably has something to do with the separation of the sabots.

Quartus
March 20, 2003, 07:11 PM
Quartus, thinking of the AMX-13 perhaps?


Jah, Joe, mebbe dots vat it vas. Been too long since I studied armor!


Thus saith the old TOW gunner. :D

Justin
March 20, 2003, 09:19 PM
Sort of to armor what the Manlicher Carcano was to sniper rifles, or the Reising to submachine guns. Or the Chau-Chat to MG's?;)

It's been awhile since I've done any heavy reading about tanks, but a few years ago I had a serious interest in armored vehicles. Until I came to the realization that I'd probably never own one.:(

ExMB
March 20, 2003, 10:27 PM
I believe the origin of the coaxial gun stems from the days before modern fire control systems. A tank crew could fire a few small(er)rounds to confirm aim before firing the main gun.

Griff
March 20, 2003, 10:38 PM
Billy Sparks-
I think the one you're talking about was the SP (self-propelled) gun called the Elefant, http://battletanks.com/elephant1.htm most famous for it's losses at the battle of Kursk.
This was a very powerful machine on paper, well armed and armored, but heavy, slow and complex, with a limitted traverse for it's 88mm main gun in a box-like enclosure for the crew where the turret should be on a regular tank.
It lacked self-protection from infantry in the form of an MG. Enemy soldiers could get in close, climb on, and use Molotov Cocktails and/or AT grenades, mines, satchel charges, etc on soft spots like engine vents, crew compartment ventilators, pistol ports, suspension, and so on. Kinda like sneaking up on a giant tortise.
A machine gun was later added, but not really coaxial, as it was ring-mounted on the commnder's cupola with a shield.

A side note: using your coax to clean attacking infantry from atop your wingman's tank was (may still be, not sure) called "picking fleas" or "scratching each others' back," not the kind of thing you'd want to do with a main gun cannister round.

Detritus
March 21, 2003, 12:21 AM
and then they built Maus (http://www.vlewis.net/maus.html) (originally call Mammut or Mamoth) a true Monster, 188 tons, the turret alone weighed 50 tons!! 5-6 man crew, main gun 128mm, the co-ax was a 75mm cannon!! . it also apears from the pictures of the sole surviving example that it was equipped with a rear mounted ball-mount MG (guess the germans paid attention to the KV-1, and thought that this was a good idea)

only two were cmpleted, one's in Kublinka russia the Germans blew the other one. something like 8 more hulls were in various build up stages when Krupp Werk was over-run.

great armor (no existing tank gun could breach it's hull) great armament... slow as a turtle with arthritis (who needs speed when even your enemies biggest tank shells bounce off). the surviving example in Kublinka, has "battle scars" (shell divits, etc) from a post war 'testing, examination, and evaluation" around 1954, impact area looks like a Rifle plate hit by small caliber pistol rounds.

CWL
March 21, 2003, 01:40 AM
Coaxial machineguns used to serve another purpose.

They used to be used as a ranging device for the main cannon.

BerettaNut92
March 22, 2003, 12:26 AM
Another question, why sabots?

Detritus
March 22, 2003, 01:18 AM
why sabots short answer "cause they work"

long answer, and others like Echo23TC can answer better, (and please do if i get this wrong..)

you can increase velocity to a truly ungodly point and still keep the chamber pressure at a SANE level, by shooting a lighter weight, thin (what is it Echo23TC? 1-2 inches?? ) DU dart 120mm smoothbore, . the concept has been around, in tanks, since WW2 (different materials) , and i think has been around the firearms world for much longer.


in case you DON'T what a Sabot round does. the round leaves the muzzle, sheds the Sabot and the actual penetrator looks lie the worlds lagest Flechette. i never can remember the MV on that sucker but it's hauling. when the thing hit armor a good bit of it's Kenetic energy is converted to Heat energy, making not only the (very small) impact site white hot but the penetrator as well. as the "dart" passes through the armor bits of it begin to Spall off, these too are white hot....

ok, enemy tank = confined sealed steel box containing, 3-4 human bodies. and in tha case of a Soviet tank an autoloader with an exposed ammo carosel.

now a white hot lance of supersonic metal flies in one side pulling a swarm of wite hot little BBs after it, and also some speculate sucking air into the entry hole, the dart passes through the other side of the tank, BUT that swarm of inferno hot BBs DOESN'T they bounce around the turret like the little hyper sonic bees they are, setting fire to everything they touch, remember that stack of ammo on the floor of the soviet tank?? well every round in it blows. the inside of that tank is now an inferno. all this happens in a split second, odds are you;re dead before you know you're hit. it might take a second for the the internal ammo to explode hard enough to blow a hatch open ad show that you're dead, but by then you're on the way to allah..

ok someone tell me if i got that right. it's been 4-5 years since i last got a description from a reservist TC i used to work with.

Navy joe
March 22, 2003, 09:18 AM
Yep, sounds like a sabot round. Actually referred to as APFSDS which is armor piercing fin stabilized discarding sabot. I don't remember the weight of the dart, but I want to say it is something like 44mm diameter. MV is in the 5,000fps range. Another fun fact. The DU rounds are safe to be around and handle, maybe not so safe after they have hit something. The uranium is pyrophoric (I think that's right) which means all that heat made from hitting the armor lights the round off, burning uranium, or fun with physics.

pwolfman
March 22, 2003, 02:32 PM
That looks like the M1 Abrams on display at the Ft. Knox Patton Museum.

Actually that is the Ordnance Museum at Aberdeen Proving Grounds. It was the first model M1 with the 105 rifled barrel with the name of ThunderBolt. Notice the fleet of armored vehicles in the rear of the picture. that museum has some amazing pieces of armor from almost every nation (that has armor) in the world. Also the home of Ordnance.

Go Ordnance!!

:cool:

Pwolfman

Dannyboy
March 23, 2003, 01:59 AM
Tune in to Foxnews to see why tanks have coaxial MG's. Impressive stuff.

Echo23TC
March 24, 2003, 10:29 AM
The 105mm dart I have on my desk is ~1 7/16" in diameter, 15 inches long, and weighs 5 lbs. The 120mm is a bit bigger, obviously. MV on the service 120mm APFSDS-T is 5280 fps.

Detritus, you have a good memory.

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