[Wild Goose]

Originally Posted by Heir of the Void

Okay, then why are they using smoothbore cannons? IRL, tanks use them because of fin-stabilized discarding-sabot and HEAT rounds (where the spinning would mess up the jet of plasticized metal). But neither of them really offer anything of worth aginst the BETA; an APFSDS round still can't front-pen a Destroyer without consecutive hits, and there's really nothing ot use a HEAT shell against.

An AP/HE shell is going to be good for taking down Fort-class, but those aren't all that common. I would think that (by far) the most useful round would be canister shot (because what 120mm caniter does to anything without heavy vehicle aror is just terrifiying), and it doesn't really require either barrel type.

...have you actually played the VN? Because they do score frontal kills against destroyers, using sabot.

Part of the problem, I suspect, is in the sabot construction - the US presumably uses DU sabot and sells it to everyone who'll buy it, but more than a few nations are using... steel. And nobody's loading HEAT into a TSF. That said, I think something like MPAT would actually work pretty well on Fort-classes, but eh. If you're using DU sabot, not only are you firing an arrow into whatever you're shooting, you're firing an arrow that shatters after penetration into a cloud of razor sharp fragments that are on fire.

As to why smoothbore guns, I will again state the reason of ammunition commonality. If you use the same ammo as the tanks, then you simplify your logistics by shipping everyone the same rounds. Note that Britain is seriously considering going to the Rheinmetall L56 120mm smoothbore gun for their next tank (if they don't just buy the Leopard 3) because nobody makes 120mm rifled ammo anymore. Same issue, really.

Canister would be great on BETA infantry forms, but it would have issues with the larger beta strains, and in the massed BETA attacks we see you really need 36mm since it's pretty much the best jack of all trades round. Sure, canister or DPICM could kill Grapplers, but 36mm DU API kills them a lot faster. (While the official sources state that TSFs are using 36mm HVAP, my own perusal of the description of the round's construction has led me to believe it's essentially an upscaled PGU-14/B, the 30mm round used in the A-10's GAU-8 Avenger cannon and the Bushmaster II.)

Also, looking at the Assault Cannon pictures, the cannon barrel seems extremely short; no more than 2.5-3 meters long if the weapon as a whole is ~8 meters (compare to the Abrams/Lepord main gun, which is 5 meters and change). With that kind of barrel length, the internal ballistics are going to be more like a mortar.

Considering that, it would need a much larger propellant charge to achieve anywhere near similar muzzle velocity. This makes sense in light of the absurdly small magazine size; in most of the Assault Cannons shown, the Chaingun mag seems only slightly larger than the cannon magizine. If my slide rule isn't lying to me, a 120mm shell should be about 37 times larger than a 36mm round, meaning you could theroitically pack 54 of them in the same volume as 2000 chaingun rounds. Packing efficiency will drop because of the larger shell and the mag isn't quite as big, but I'd still expect at least four or five times as many rounds per mag, which fits with the idea of a larger powder charge.

Well, with tank guns they're as long as they are so that you can throw rounds out to 2km plus and be sure they'll hit. I do freely admit that the short barrel is a problem - I can only speculate that it was considered an acceptable tradeoff in light of the fact that TSFs tend to fight closer to BETA than tanks should. *shrug* Military design is full of tradeoffs, in the end. I should also add that your math is a liiitle iffy, and that trying to pack in that many 120mm rounds into an underbarrel magazine would lead to weight distribution and balance issues for the rifle. :V Remember, it's the difference between a single stack magazine carrying 120mm rounds with casings and all - and don't forget the casing is wider than 120mm! - and the difference between 36mm caseless rounds.

A shorter barrel means less muzzle velocity, which is going to adversely affect people using tungsten and steel sabot, because they need muzzle velocity to pen. Because the US uses DU sabot, and DU is significantly denser than tungsten, you can get similar penetration with less velocity. (Now I need to go back to Spacebattles to find Connor MacLeod's many posts about this.) But yes, sabot rounds aren't going to perform as well fired out of the underbarrel 120mm compared to the full length tank gun. But they're still going to work better than any other round you could load in.

IMO anything more than 10 rounds is kinda pushing it for a single stack mag (plus the question of how the hell are the rounds feeding into the breach - it's not like they've got a team of fairy loaders there :V).

Well, how else are you going to reduce the threat? Throw the ships of the UN 3rd fleet one by one into the path of the lasers?

When I say losing proposition, what I really should have said was that it is not sustainable beyond a single engagement, because if you're going to try and spam arty at lasers, you're going to run out of shells, you'll wear out your barrels, and your entire arty battalion is now combat ineffective.

Also, Ouka is not a good support for your argument, given that they did conduct AL bombardment, but the Superior, having assumed direct control, ignored the AL smoke to focus on the HSSTs. This is also what fucked the divers; they landed, and then the dense metal cloud rounds landed on top of them and acted as KE projectiles. (This is because these rounds are designed to vaporise into AL smoke when shot at by lasers. When lasers don't shoot them, they're basically inert metal. This is an oversimplification.)

Anyway, each laser has a minimum interval of 12 seconds between shots. Assuming perfect accuracy, that means it can shoot down five shells a minute.

The standard WarPac piece (2S19 MASTA) in U/A has a peak fire rate of 8 rpm, meaning that a 57 gun battalion fires a peak 456 rounds per minute, meaning it's going to need at least 91 lasers to stalemate it.

But that's Warsaw Pact. A U.S. Crusader SP Gun has a peak rate of fire of 12 rpm (with active barrel cooling for sustained rapid-fire), meaning it's going to need at least 2.4 lasers to stalemate each gun. That's at least 136 lasers.

I want to point out the major flaw in your assumption here: you assume that Lasers fire in pulses. That's not correct. They fire in sustained beams. So a Laser is going to be able to kill more than 5 rounds per minute. The lasers fire and sweep the sky - that's how they take out the bombardment. Hell, Sadogashima: the lasers basically no sell'd a sustained bombardment and the hive was undamaged. Goddamn where the hell is that gif when I need it...

But this, of course, is forgetting the MLRS. 12 rockets in 'less than forty' seconds for the real-life version, presumably the designers of the U/A version would be aware of the presence of lasers and thus spec their system to do at least as well. Once you have the lasers focusing on the howitzers, you hammer them with a MLRS battery, dumping several dozen rockets on them in the time they can fire maybe twice. And if you can wear down the number of lasers present, that makes the whole job a lot easier.

This actually assumes you can find the lasers, though. Remember, air recon is pretty much out because the Lasers home in on electronics and silicon - the more high tech it is, the more Lasers assign targeting priority to it. (My pet theory is passive electrolocation, though the other answer of "Lasers are bullshit" is also acceptable. :V)

That's the whole reason Laserjagd is such a thing: use sat recon or other assets to try and figure the general location of the lasers, then send Laserjagd squadron to take them out. In that respect it's not that different from Wild Weasel/DEAD missions.

And them there's AL rounds. Laying down a heavy metal cloud makes artillery more effective, though I cannot find any hard-and-fast rules on the extent.

Sure, but this requires you to drop dense metal rounds on them in the first place, and you then need to alternate between AL smoke and HE, and eventually you're going to hit diminishing returns with how much AL smoke you can fire.