How does an A-10 cannon kill tanks?

Density is important, but the density for tungsten is only higher by a little bit, and it’s certainly not the only factor. Tungsten does find use in certain penetrators, but according to the below article, DU has some other things going for it.

I’d like to return to this part of the OP:

Which 105 rounds?

Artillery for example is generally not equipped to shoot tanks. It’s an area weapon and the shells are all about blast and fragments. A direct hit on any vehicle in the field is very unlikely in the first place. And even a near miss will do little other than perhaps dislodge a tread or damage some optics if very very lucky. Most likely it just results in some extra noise for the tank crew to put up with while fighting.

There are other direct fire weapons in the general 105mm range, but until we know which one(s) the OP is talking about we can’t address why it is, or is not, surprising that they’re ineffective against tanks.

TLDR: There’s a lot more to weapon effectiveness against any particular target than simply bigger boom = greater damage. And this is especially true against hardened targets, whether that concrete bunkers or armored vehicles.

To LSLGuy, or really anyone in this thread:

I could be confused, but while it’s commonplace to refer to shell diameter, my understanding is that shell size only loosely correlates to battlefield performance. All things being equal, sure - a a larger shell will deliver more kinetic energy. But obviously in the real world there are big trade-offs involved and you don’t really want larger shells if you can help it, right?

So I’m not sure I understand Velocity’s statement. It raises the question of which shell, which armor, what gun & etc.

The key thing with modern highly-engineered weapons is there are lots of kinds of shells of any given size. Some for killing people in the open that are ineffective against APCs; some that are for killing APCs that are less effective at killing people and ineffective at killing tanks, some that ideal for tanks but nearly ineffective at the other roles, etc. Bunker breeching is different from tank breeching as well.

All else equal, any military wants to pack the most punch into the smallest cheapest package. That way they can buy more and carry more. So in that sense smaller is better. But not so small as to lose the desired effectiveness. At some point smaller stops being cheaper and starts getting more expensive per round. So that’s a tradeoff too.

The downside to highly tailored munitions is now you need to carry some of each or your battery becomes a one-trick pony. Some jobs, like anti-aircraft gunnery vs anti-tank gunnery are so different you need different guns and different ammo and different aiming and different command and control to do the job. With all those differences, the ammo is not sensibly comparable.

The OP’s question is reasonable. But it’s a very one-dimensional question about what’s really a 10-dimensional optimization equation.

AIUI, the A-10’s cannon is loaded with a mix of rounds: some are explosive (i.e. each projectile is a tiny grenade with an impact-sensing fuze in its tip), and some are armor-piercing DU. I don’t know whether they tailor that blend for any given mission though.

I admittedly can’t find the source again. But I distinctly recall reading about how some tank guns in that mm range (105mm) were found to be unable to penetrate certain other heavily armored tanks. That was all the cite was.

Anyhow, I was wondering what a 30mm aircraft shell could do. I guess it is much more about location, as others said (top armor is thinner, hitting treads also can work.)

WHAT “anticipated near-peer battlefield?” There aren’t any left. I don’t think the Russians are going to be pouring through the Fulda Gap any time soon, and armor is virtually useless throughout most of Korea due to terrain issues. Any wars the US is going to be fighting are going to be against inferior forces or nuclear. Or in space or cyberspace. There is never going to be a Kursk or Bulge involving US forces.

Ref wiki they load 5 of the DU API rounds to 1 HEI explosive round.

In the 20mm M61 I used to use we loaded pure HEI if we were going after airplanes and/or thin skinned ground targets. We’d load a mix that was mostly API if the target set was mechanized infantry or armor. Not that we expected to have any success against the frontal armor of then-current T-72s. But for lesser vehicles or side or rear attacks the books said we’d be effective enough. I never had the chance to try it for real myself, but there have been 20mm strafe attacks in the Mideast since.

Tank armor has gotten a lot better over the years. Hard data is tough to find, but I’d not be surprised to learn that the 105mm gun in a US M60 tank using rounds from when it was introduced in the late 1950s would be ineffective against the frontal armor of a US M1 tank fielded in the 1980s.

Back in the day anti-tank rounds were either hardened steel and later self-forging projectiles or shaped charges. Much later came the discarding sabot. See

for lots on the history of some pretty amazing engineering. The see-alsos on that article aren’t great. Try looking up HESH, HEAT, explosively formed projectile, kinetic energy penetrator, and shaped charge. Plus their see-alsos.

The modern 120mm (~=4.75")gun in an M1 tank fires a round where the actual impactor that hits the target is about only 1-1/2" in diameter. Not too far of the size of the impactor in the A-10 GAU-8 cannon…

Several somewhat outdated MBT had the 105 as their main weapon. M60, AMX30, Leopard, etc.

The current Stryker Mobile gun system carries an updated 105mm cannon and the latest 105mm DU, HEAT, HE, and canister rounds. more from wiki here:

Comment on HEAT rounds/shaped charges. Armor/concrete/earth penetration is the same mechanism as a solid penetrator round - kinetic energy. The “shaped” charge focuses an extreme pressure front on a tiny area. The armor/etc. is forced to flow (it’s an elastic flow) away from the focused pressure front. It looks like it was melted but that’s from the pressure flow. Modern HEAT rounds will have a cone/hollow made of copper alloy. This is an aid to focusing the explosive wave shock front but not required1. The cone is crushed into a jet (also called a slug) which follows the pressure pulse through the armor/etc… Spall from the inside of the armor, overpressure and the jet ignite anything in the target (ammo/fuel/hydraulic fluids). The blast overpressure kills the crew along with internal explosions, fragments, and fire. Kind of a black goo remnant.

1 the shaped charge effect can be made by making a depression in an explosive in the shape of a cone, “v”, or hemisphere. No liner is required. Current materials for liners in US shaped charge munitions include, glass, steel, aluminum, DU, but are predominately copper alloy. Multiple (tandem) shape charges are used in the latest munitions to defeat layered reactive armor tiles.

The impact area for a HEAT round or penetrator round look very similar. The HEAT round will leave an area of fragment indentations from the the body of the round. The penetrator round will not have the characteristic fragment splatter. See image below.

I’m sure he means guns like the
L7 and derived guns. It’s true that even with their best penetrators they have some difficulty penetrating the best armor on some modern tanks (T-72B/T-90, T-80, T-14, etc) and that’s why we use the Rheinmetal 120/44 and even 120/55 now as the main armament of NATO tanks.

As an aside, is there a shittier job in the military than being a tank crew? It sounds like a tank is a bullet magnet. I guess a battle ship is similar in some respects but those seem to be equipped with some anti-projectile defense systems.

Smithsb, do the ‘slugs’ from Misznay-Schardin shaped charges have similar terminal effects to the ‘jets’ from Munroe-effect shaped charges, or are they more similar to long-rod penetrators? Obviously, the slugs are going quite a bit slower, and I think they’re considerably broader as well.

Silenus, the near peer is likely going to be China. It has been Russia, if we count their mercenary companies, in the very recent past. If GAAT silliness got any worse—though it looks like Armenia-Azerbaijan is done for the time being—it might conceivably have happened there too. God knows, the US Army did enough staff work familiarizing itself with the area in the early Oughts.

No, there won’t likely be A-10s shooting bullets at Type-99As any time soon. (Though the terrain in Korea is not impassible for armored forces at all; merely an easily channeled, PITA to operate them within, per Fehrenbach on the Korean War, and later studies afterwards. Not that anyone wants to fight in Korea anytime soon. ) The A-10 platform does do a lot of CAS work besides tank-killing, and as already noted, the gun isn’t suited as it was for killing modern MBTs.

Modern IADS are supposed to be nothing to mess with, and the key to not getting hit by them is supposedly to not be seen in the first place. Hence the drive to build a gazillion F-35s, and using stuff like HIMARS. (How stealthy are things like HIMARS or artillery-delivered ordnance anyway? In a world with things like Firefinder radars, stealthy ordnance would seem to help with the counter battery problem. Speaking of other things the US is going to have to learn to live with again, in a near-peer fight.)

I’m not a military member. I do talk to them though, and they’ve indicated their bosses are starting to get paranoid about all of the above. As silly as fighting a major fight with either China or Russia sounds right now. OTOH, it could be the MIC making boogeyman shadow puppets on the wall to justify new funding.

Moving towards stealthy delivery of ordnance within and beyond the FEBA seems to me—again, not a military guy—to radically change how the platoon or company commander in the fight gets additional fires upon a target. The perception I’ve read is that most fixed-wing CAS is too unwieldy in its operation, including things like deconfliction, to be of much utility in the COIN battles within e.g., Afghanistan. The Air Tasking Order is too complicated, needs to be done too far in advance, whatever. Rotary-wing assets, and stuff like AC-130s and Reapers for the cool guys, are far more responsive. But they aren’t stealthy. I guess they can always call in artillery.

Since this has become a tank thread, this video is always good to watch:

It shows the effect of normal rounds (ineffective), Squash rounds (causes spalling, unless tank has anti-spall liner,) sabots (scatters metal fragments inside compartment,) and HEAT rounds.

The Misznay-Schardin (MS 'cause I don’t want to type that again) are a “plate charge”. Also known as Explosively Formed Projectiles EFPs. They are a kinetic energy round related to the Sabot tank rounds - solid rod penetrators. The earliest/simplest were sticks of dynamite or other explosive attached to the underside of a manhole cover. Remotely detonated when the tank/vehicle passed over the cover. The center of the cover would bow upward making a blunt penetrator round. The underside of tanks are thin on armor as well.

Some US weapons using the EFPs are TOW2B missiles and Remote Anti-Armor Mines RAAM submunitions ejected from a 155mm projectile body. Also see Gator, Volcano in the Family of Scatterable Mines (FASCM). Also a SADARM munition (Sense and Destroy ARMor) uses an EFP as the kill mechanism.

More about the SADARM in a 155mm projectile. Wiki:
Wiki show the projectile as in developement in the late 80s, some poor test results in 1993 and then more development and successful testing in 1995. Also combat use in 2003, Desert Storm II Electric Boogaloo. I was in Saudi Arabia (and Iraq and Kuwait) during the Original Desert Storm. We had a single pallet (24 rounds) of the experiments rounds. They were not fired to my knowledge and were probably shipped back for the later tests. Also weird that we had experimental pallets of 155mm Electronic Jamming Projectiles (supposedly just developmental); 155mm HEERBB projectiles - 155mm High Explosive Extended Range Base Bleed rounds (not rocket assisted); and 155mm empty cargo projectiles (M483 bodies) designated as leaflet rounds (please surrender!). Crazy stuff that were supposed to be “future” rounds but were on hand NOW/then.

EFPs can also be called Self Forging Fragments for more trivia.