Military Ground Vehicles of Your Nation [NO MECHS] Type 6

[Anemos Major]

except

penetration isn't binary

kiev had such a nice infographic showing the probability of penetrating various armored vehicles with HEAT

'Except' what? You repeat this mantra time and time again, but I'm not sure you're entirely aware of what you mean - whatever the case, I've already considered this point above. No, penetration is not binary, but I'm talking about the 'frontal protection of current-generation main battle tanks', which is really rather particular. And if you look at his infographic, I daresay that HEAT will be adequately absorbed by the protection of composite armoured tanks from 1980 onwards or so, and KEPs will find themselves in trouble between 1985-1995 or so and onwards.

I'm not denying the utility of HEAT, but I think it's safe to suggest that most modern militaries don't consider HEAT in its current form, fired out of current guns frontally towards the enemy, sufficient to defeat main battle tanks that aren't twenty year old monkey models - the proof is in the testing and the subsequent developments, then procurement and loadouts. What I'm suggesting on top of that is that, much in the same way that a theoretical reappraisal of the penetration characteristics of KEPs radically changed the approach taken towards their design in the 90s and onwards, a similar reappraisal of HEAT may well be at play right now that will bring them back onto the frontline in earnest, in the role they were originally intended to fulfill. That's pure speculation, but if you consider the fashion in which HEAT is defeated by modern composite arrays, it's not hard to see what you'd want to change to reoptimise them against what they now face.

So no, penetration is not binary - and given what I've said, overall, above, I think that's both abundantly clear and actually elaborated further upon.

with populations of billions, and a GDP/capita equal to that of the United States, the ability to concentrate military power in a single to decisively enforce your objectives is most vital

'High velocity freedom'.

I guess.

I always thought that the two types were both pretty useful and good at killing stuff, while HEAT excelled in killing everything else short of an MBT, while KEPs pretty much were only good at killing tanks.

Eeh. This is less a matter of 'vehicle types' and more a matter of what those vehicles are protected by and what exactly it is that's hitting them. For example, assuming you're using a 120mm L/44 smoothbore gun or something therabouts...

- A current-generation APFSDS will probably do a fairly good job of shearing through the frontal protection of, say, an initial production M1.
- A current-generation APFSDS will, on the other hand, do a slightly less good job upon hitting the frontal protection of the M1A2.
- A HEAT round will do a decent job shearing through the unprotected front of an IFV, most likely.
- On the other hand, unless it's tandem-warhead (and even that doesn't guarantee anything - it has a lot to do with how that tandem warhead interacts with the IFV's protection), ERA blocks are going to disrupt the HEAT round's jet and bugger up its penetration.
- Meanwhile, a top-kill HEAT warhead (much easier to achieve than a top-kill KEP) is going to do a decent job of trashing a main battle tank.

And so on and so forth. On top of that, there's a difference between, say, a HEAT round and a HEAT round with a fragmentation/shaped charge warhead - the former is questionably useful in a traditional 'HE-Frag' role, the latter does somewhat better in that capacity. It's arguably the big reason why HEAT has been kept on in Western militaries - because it can be used to engage infantry clusters, light vehicles, fortified positions and helicopters all with one round in current iterations, which frees up a considerable amount of space in the ammunition racks.

The above are all, of course, general and fluffy terms, but what you see is a state of affairs where the ability of a 'particular round' is actually wildly variable depending on what it is and what it's facing. In this particular case, the rounds in question are current and potential near-future, 120-125mm APFSDS and HEAT-MP, and the 'targets' I'm considering are current-generation MBTs.

[Chebucto Provinces]

Now that I have time. I will reiterate that we are speaking of a tank who's introduction is 1991 at the latest. Who's ability to use legacy 105mm ammunition is paramount, especially in the need to employ more then just two types of rounds. Its role is as direct fire support, in support of Chebucto infantry deployed abroad, not repeat-the-battle-of-kursk. It can reasonably expect to be the newest tank on the battlefield more then half of the time when deployed.

Everything up to the last three words, alas. Consider it thus - at the point at which you have a 105mm capable of resisting and housing the pressure necessary, and equipped with a KEP capable enough to, engage and destroy a 'modern MBT', you'll have expended a ton of money essentially creating a weapon that shares zero commonality with legacy 105mm options. In which case, you might as well go ahead and opt for a 120mm option, which is a fairly cheap, given the above, way of achieving something similar to some extent.

I do not follow how a weapon designed to take higher pressure rounds without failure but to the same internal dimensions as existing guns can not be made.RO clearly did it.
120mm in the post cold-war situation is very cheap. But moving to it in this program is not compatible with the operational needs, and therefore not cheap.

I will caveat though: This is not the same situation in 2010-2014 when the replacement for this tank is being developed.

'High-performance' 105mm guns, for the most part, are really a phenomenon that post-dated the development of the 120mm smoothbore.

And are in the very realm which we are looking at.

The logic is fairly simple - with the fall of the Warsaw Pact, instead of having to consider ever-larger calibres and rounds to destroy expected ever-larger threats, the NATO-and-friends nations (not quite the 'forces of the free world') found themselves in a position where 120mm and 105mm stocks were both all they were going to get funding for, and all they really needed in the immediate to short term. Add to that the renewed recent onus on 'expeditionary' capabilities (embodied in figures such as Eric Shinseki over in the US), and what you'll find is that 105mm guns have in fact matured over recent years because of this duo of post-Cold War lines of reasoning.

The reality of Chebucto doctrine is that this "expeditionary" focus where 105mm is adequate or can be made adequate, and where stocks of 105mm ammunition are what's coming only, is the case. It is cheaper to introduce new guns with the new tanks, and a small selection of new ammo while maintaining use of the existing stockpiles, then to introduce a new gun which does not have the required munitions. New guns, new ammo, new stocks, too much cost.

Essentially, where 105mm upgrade programs were in existence before the end of the Cold War, their revival and further development (and adoption) was the result of a whole host of nations realising that they needed to bring the rest of their tanks up to scratch in the absence of any potential future procurement.

As said, we're looking in a time frame where they have not been revived, they are still there.

But the issue is that you can't actually use existing stocks to create the 105mm high velocity gun you're conceptualising. Consider it thus. To increase penetration, you need a better round. To allow for a better round, you need to increase the gun's pressure tolerances (and possibly remove the rifling) - and that involves altering both the barrel and the breech. To house a different breech, you need a different mounting... see where this is going?

See previous comment regarding RO doing just that in the same time period.

[Anemos Major]

現在運用されているAPFSDSは93式装弾筒付翼安定徹甲弾が使用されている。この弾薬はダイキン工業が開発したもので、初速は1501m/s、装甲貫徹力は射距離2kmで414mm程度の均質圧延鋼版を貫徹可能と推定されており、これは第二世代戦車相手なら概ね正面装甲を貫徹可能なレベルである。ちなみ導入当初に運用されていたL28A1 105mmAPDS弾の装甲貫徹力は同条件で240mm程度、1984年に導入されたM735 105mmAPFSDSで318mm程度であり、当初に比べれば攻撃力は大幅に向上していると言えよう。

Yeah, but the key operating term here is '推定', which changes quite a lot. With that margin of error, added on top of the fact that the JMoD was willing to fund the replacement of 105mm ammunition stocks with this new stuff going into 2001 (some ten years after the Cold War ended, and a while before the 105mm MCV was conceptualised), it's not that hard to suggest that it's going to be achieving similar levels of performance to what DM33 what achieving in early JGSDF guns. At least, that's the TRDI sell - 'comparable to legacy 120mm guns'.

Incidentally, we've reached the point where MECAR has a 105mm APFSDS that can achieve ~460mm of penetration under the same conditions out of legacy guns - given the tentative suggestions that the Japanese are going to be developing a successor to the Type 93 in current service for the MCV (now that it's supposed to be a tank), we'll probably be seeing an even sillier rifled 105mm APFSDS round soon enough.

[Anemos Major]

This is my Nomination. There are many like it, but this one is mine.
Nominee: The Kievan People

Alright, it's now Page 270 - please do get your nominations in by the end of this page. Once we reach 271, nominations will be closed and I'll put up a poll.

[Anemos Major]

Now that I have time. I will reiterate that we are speaking of a tank who's introduction is 1991 at the latest. Who's ability to use legacy 105mm ammunition is paramount, especially in the need to employ more then just two types of rounds. Its role is as direct fire support, in support of Chebucto infantry deployed abroad, not repeat-the-battle-of-kursk. It can reasonably expect to be the newest tank on the battlefield more then half of the time when deployed.

- Ability to use legacy ammunition
- Fire support, not tank destroyer

So essentially, a sort-of-Stryker MGS. Righto.

I do not follow how a weapon designed to take higher pressure rounds without failure but to the same internal dimensions as existing guns can not be made.RO clearly did it.
120mm in the post cold-war situation is very cheap. But moving to it in this program is not compatible with the operational needs, and therefore not cheap.

I will caveat though: This is not the same situation in 2010-2014 when the replacement for this tank is being developed.

But Royal Ordnance did it with a new gun, and new ammunition. So that doesn't actually satisfy your requirements.

This is a big part of why IWS didn't actually score new customers (as a tech demonstrator, it's a decent example of how '105mm rifled' as a generic category can be used to achieve fairly significant muzzle velocities with APFSDS rounds, but it's a new build weapon and ammunition). It's not what you'd be looking for in the slightest. So what you're saying is 'here a 105mm gun that does fairly well but isn't what I'm looking at, here's what I'm looking for in a 105mm gun, ergo I should be able to combine the former with the latter', which is a non sequitur.

Given that you'd be paying a premium to produce this sophisticated new gun and ammunition, whether it's cheaper or not is somewhat up in the air.

And are in the very realm which we are looking at.

Not with legacy ammunition, it's not. It's never been done with legacy ammunition, because legacy ammunition isn't exactly high performance. On the other hand, if you're looking for legacy guns coupled with new ammunition, that's very much a 1990s+ phenomenon - not the sort of thing you'd see in a tank brought into service in '91.

[quote="Chebucto Provinces";p="20547117"The reality of Chebucto doctrine is that this "expeditionary" focus where 105mm is adequate or can be made adequate, and where stocks of 105mm ammunition are what's coming only, is the case. It is cheaper to introduce new guns with the new tanks, and a small selection of new ammo while maintaining use of the existing stockpiles, then to introduce a new gun which does not have the required munitions. New guns, new ammo, new stocks, too much cost.[/quote]

In which case, you can only really expect legacy performance from these new tanks with new guns and old ammunition. Stryker, which you seem to be misperceiving somewhat, is a perfect example of this - the legacy ammunition it fires from its modified gun is only really going to achieve legacy results. That's fine, but sort of a downgrade, because you're looking at a gun and munitions that were once loaded up onto a main battle tank now being used in a direct support role. But the 'new' rounds that are supposed to be particular to the 105mm rifled gun are hardly new - both HEAT-MP-T and Canister are used on the M256 - so it's really a matter of creating a budget support vehicle which meets different expectations through the use of modified M60A3 guns and existing ammunition stocks to some extent.

The problem here, of course, is that you're looking at a vehicle twenty to thirty years later using the guns and ammunition of what was once a fairly heavy main battle tank in a different role. So, in essence, for you to have these ammunition stocks in place, you'd have had to have had a main battle tank of some sort toting the same weapon earlier on.

[Oaledonia]

現在運用されているAPFSDSは93式装弾筒付翼安定徹甲弾が使用されている。この弾薬はダイキン工業が開発したもので、初速は1501m/s、装甲貫徹力は射距離2kmで414mm程度の均質圧延鋼版を貫徹可能と推定されており、これは第二世代戦車相手なら概ね正面装甲を貫徹可能なレベルである。ちなみ導入当初に運用されていたL28A1 105mmAPDS弾の装甲貫徹力は同条件で240mm程度、1984年に導入されたM735 105mmAPFSDSで318mm程度であり、当初に比べれば攻撃力は大幅に向上していると言えよう。

Daikin is crazy.

[Anemos Major]

Daikin is crazy.

They are, really - though most of the big contracts go to JSW.

For the record, Daikin are the ones who allegedly developed the rumoured 135mm, 2kms smoothbore gun that's supposed to have formed the technological basis of the 120mm gun installed in the Type 10 back in the late 90s.

[The Republic of Lanos]

This is my Nomination. There are many like it, but this one is mine.
Nominee: Oaledonia

[Consortium of Manchukuo]

If, somewhat on the topic of older guns, how expensive and is it feasible to modify tank guns currently on tanks to new standards with muzzle brakes and such equipment for usage on other platform? Like for example, would it be possible to take a 120mm/L44 previously fitted on a tank and refit it with a muzzle brake so that one could fit it onto a mobile gun system, instead of building entirely new guns for it?

The reason I ask this is because I've decided my military would be one of those that never throws away anything if they can help it, like the Russians to an extent. Since it was starved of funding for a while(Not so much anymore but I figure that it would develop its culture from the period when it was), it had to make do with what it had. Thus, if equipment became aged, it was upgraded as much as possible until it simply couldn't be upgraded further. Then it was converted into something else and kept in service until it finally couldn't see any conceivable use, and then finally scrapped. So for example, a lot of the early Type 26-Series 90 which are roughly the equivalent of a worse M47 Patton, were kept on in service until a few decades ago as driver training vehicles, armored recovery vehicles, fire fighting vehicles, so on and so forth, until they themselves were replaced with the early versions of the Type 26 Series 100, and finally scrapped because they were simply of no use by that stage due to the strain and wear on their chassises and technical obsolescence. The Series 100 are probably still in service for the most part in different roles, self propelled guns that are due for replacement, OPFOR vehicles, driver training vehicles, so on and so forth. The only Type 26 series units that are in full service are the Type 26 Series 127, but those too are being retired as Model 78s arrive to replace them. Chassises are mostly being used for self-propelled anti-air guns for usage in armored divisions, along with new turrets and upgraded mobility and all that.

But what could be done with the former guns? The 127s incorporated a 127mm/45 gun that is the predecessor of the 127mm/52. They're not obsolete, although the tanks themselves are, and they can handle all but the most modern APFSDS ammunition. At the same time there aren't any chassises that will take the 127mm/45 as it stands that can't take the 127mm/52 with the natural increases in combat effectiveness from the more modern gun. There are also predecessor guns of the 90mm and 100mm, but they are obsolete by now and so are scrapped.

So, how easy would it be to provide a new muzzle break, and an autoloading system to these older guns, and fit them to a mobile gun system? I was initially planning to have the mobile gun systems being equipped with a variant of the 127mm/52 gun that has a muzzle brake, but it seems like a shame to just throw away all of these perfectly good 127mm/45s. While the MGSs would have to be upgraded eventually with the 127mm/52 to ensure full capability to engage enemy tanks frontally, the 127mm/45 would still be adequate for engaging from the side and rear, and probably taking out all but the most modern enemy MBTs frontally, as well as being able to fire top attack ammunition in cases where they're not able to penetrate frontally as effectively.

But while I like the idea of using the older guns in such a fashion and keeping them on in service in this manner for a few decades more, at which point they'll either be shifted to something else that might be able to use them or transferred to reserve/scrapped, I don't know how feasible it is to add on the appropriate adjustments to them, or if its even worth it. The best equivalent to the 127mm/45 is the 120mm/44, so I guess that is what I would use as my RL attempt to show clear examples. I haven't heard any such stories of modern guns that are to be out of service being dismounted and placed on new vehicles(I'm aware the 120mm/L44 is still a perfectly good tank gun and it is just some militaries that don't have access to some new ammunition types that are replacing it as well), but maybe that is just because of my ignorance. So the basic final question is, is it viable to upgrade this to make it work for a MGS, and is the money and time saved worth justifying the capability gap?

Edit: Also, just to clarify because re-reading this a couple times I'm not sure if it was appropriately expressed, I don't mean build more of the previous 127mm/45 guns. I mean physically remove them from current tanks that are in service and mount them on new chassises ore systems after modifications.

[Anemos Major]

[LIST UPDATED TO THIS POINT]

[Suid-Ostaskari]

This is my Nomination. There are many like it, but this one is mine.
Nominee: Questers

[Anemos Major]

snip

tl;dr yes, has happened, will continue to happen. The long and the short of it is, a legacy gun can be retrofitted to do other things, but the less you modify it, the less ideal it'll often be. For example - the M68A2 on the Stryker MGS, given its muzzle brake, probably has a new-build barrel too. You can see the obvious disadvantages of having a suboptimal barrel fitted with a muzzle brake on a high pressure gun. Or the new 105mm rifled gun on the Japanese Manoeuvre Combat Vehicle - more expensive to build, but also more amenable to the projected 'successor' ammunition they're said to be developing to replace the Type 91+93 it currently uses.

Adding a new muzzle brake: to make this work properly, you'll probably have to configure, and thus rebuild, the barrel entirely. Do bear in mind that low-recoil also entails better buffers down by the breech as well, and also that muzzle brakes are going to affect the ability of infantry to operate near the vehicle.
Autoloading system: not as hard - in this case, it's mostly a matter of building the autoloader around the gun more than anything.

Capability-gap wise, this depends a lot on what this legacy weapons system is like, what it's now supposed to do, and what you'll need to change to shift from the former platform to the latter. Modifying a legacy 105mm tank gun to sit on top of an infantry support vehicle with a muzzle brake isn't all that controversial, for example, while getting a 120mm gun to do the same thing on a similarly sized 'tank-destroyer' is somewhat more difficult. Furthermore, modifying a legacy 105mm tank gun to sit on top of this infantry support vehicle isn't all that bad, but trying to get the same weapons system to do the same thing on a 'tank destroyer' is a different question - in the latter case, it'd have to be modified, but how far can you go before it becomes cost inefficient?

So - no absolute answers, alas.

[Lemanrussland]

This is my Nomination. There are many like it, but this one is mine.
Nominee: The Kievan People

[Oaledonia]

Daikin is crazy.

They are, really - though most of the big contracts go to JSW.

For the record, Daikin are the ones who allegedly developed the rumoured 135mm, 2kms smoothbore gun that's supposed to have formed the technological basis of the 120mm gun installed in the Type 10 back in the late 90s.

The only reason they got involved in the defense industry was to install A/C on all of the tanks they helped produce :c

[Arkandros]

just a thought I had the other day- Could one use a polygonal rifled barrel on a tank gun? If my understanding is correct, the polygonal rifling would have superior performance in terms of durability relative to a rifled barrel and higher accuracy relative to a smoothbore.

[Anemos Major]

The only reason they got involved in the defense industry was to install A/C on all of the tanks they helped produce :c

I swear they have a pretty considerable market share of anything involving the GSDF and 'air' that isn't reverse engineered from American stuff.

like, no jokes, they make the fire extinguishers in a fair few GSDF helicopters and mundane stuff like that

on top of the shells, warheads, fuzes, sensors, aircraft components, medical equipment (including, of course, oxygen tanks) and so on and so forth that they self-profess to making for the SDF

[Consortium of Manchukuo]

snip

tl;dr yes, has happened, will continue to happen. The long and the short of it is, a legacy gun can be retrofitted to do other things, but the less you modify it, the less ideal it'll often be. For example - the M68A2 on the Stryker MGS, given its muzzle brake, probably has a new-build barrel too. You can see the obvious disadvantages of having a suboptimal barrel fitted with a muzzle brake on a high pressure gun. Or the new 105mm rifled gun on the Japanese Manoeuvre Combat Vehicle - more expensive to build, but also more amenable to the projected 'successor' ammunition they're said to be developing to replace the Type 91+93 it currently uses.

Adding a new muzzle brake: to make this work properly, you'll probably have to configure, and thus rebuild, the barrel entirely. Do bear in mind that low-recoil also entails better buffers down by the breech as well, and also that muzzle brakes are going to affect the ability of infantry to operate near the vehicle.
Autoloading system: not as hard - in this case, it's mostly a matter of building the autoloader around the gun more than anything.

Capability-gap wise, this depends a lot on what this legacy weapons system is like, what it's now supposed to do, and what you'll need to change to shift from the former platform to the latter. Modifying a legacy 105mm tank gun to sit on top of an infantry support vehicle with a muzzle brake isn't all that controversial, for example, while getting a 120mm gun to do the same thing on a similarly sized 'tank-destroyer' is somewhat more difficult. Furthermore, modifying a legacy 105mm tank gun to sit on top of this infantry support vehicle isn't all that bad, but trying to get the same weapons system to do the same thing on a 'tank destroyer' is a different question - in the latter case, it'd have to be modified, but how far can you go before it becomes cost inefficient?

So - no absolute answers, alas.

Thanks for the information. It sounds like it wouldn't be as easy to use the 127mm/45s on the new platforms as I had hoped for. I had been hoping I could just shove on a new muzzle brake and an autoloader and would be good to go, but having to replace the entire barrel means that it'll still cost a fair sum, and its going to be fundamentally inferior to the later gun. Although I like the idea of keeping the 127mm/45 in service for a significantly longer period of time than otherwise, I guess it is just going to have to be shuffled off to reserve formations. 127mm/52.Mle.71M2/MBs which are the muzzle brake equipped version of the 127mm/52 will have a low enough recoil for mounting on mid sized platform, and lighter units would have trouble fitting a 127mm/45 anyway and if they do get a gun system they'll probably be of 76mm-90mm-100mm instead. The only major advantages L/45 have over L/52 as far as my guns go are decreased cost and very slightly decreased recoil, and if the cost advantage isn't there to enough of an extent to outweigh the capability loss, then I have no real reason to keep on using the L/45s. I guess just keeping them in reserve to replace worn out L/45s instead of just redoing their barrel to get rid of them will solve their presence neatly enough in time.

[Chebucto Provinces]

Sorry Anemos but I'm on my phone so this has to be in point form. Massive quotes on this thing don't work.

The MGS fills the same role as this yes. Picture it more specifically the role of tanks in Kosovo or Afghanistan.

The RO IWS was fully capable of using old L7 munitions. There was nothing keeping it from doing so. I think you are assuming I mean to attain performance gains using the legacy munitions. Rather I am looking to gain performance gain with new munitions while maintaining the ability to use the legacy munitions.

It is, however, cheaper. The cost of the new gun is in the cost of the new tank. The cost of the new round is additional. The savings come from legacy munitions carrying over and the ability to maintain that legacy stock for use. Or, for example, to use it for reserve tanks using the legacy L7 which will only lose out on the new gun and new ammo for it.

I'm not sure if you understand how the intent to use legacy munitions is held here. The tank is expected to hold its own against expected threats. Upon introduction this means T-72B sans ERA or less. This is perfectly.achievable in 1990 from an IWS like gun with new round. The legacy stocks come from the previous tank which used the L7, and are intended to achieve no more then their design, but their continued use is preferable.

When common threats change in the mid-late 1990s then things change. Hence a replacement project for the tank I am working out. But that is not the frame of reference here.

[The Kievan People]

By popular demand. Disclaimer: I am not sure if this is trying to to indicate the chance of the weapon striking a surface it can penetrate or the chance of penetrating a certain surface, or both.

[The Akasha Colony]

Now that I have time. I will reiterate that we are speaking of a tank who's introduction is 1991 at the latest. Who's ability to use legacy 105mm ammunition is paramount, especially in the need to employ more then just two types of rounds. Its role is as direct fire support, in support of Chebucto infantry deployed abroad, not repeat-the-battle-of-kursk. It can reasonably expect to be the newest tank on the battlefield more then half of the time when deployed.

I think the most relevant question here is, why is it so critical that legacy ammunition stockpiles be used?

The primary justification seems to be cost, but you have already incurred the cost of designing what is functionally an entirely new gun that shares only its caliber with its predecessor. So there are no real savings to be had there. I would also guess a new FCS would be developed to be paired with the gun, which is also a not-insignificant cost to procure. And possibly a new recoil system to handle the extra power.

Meanwhile, on the ammo front, you still incur the costs of developing new rounds to take advantage of the improved gun, and presumably fielding at least some of these rounds. It's also possible the rather interesting round types you'd need to claim penetration of more advanced armor arrays would cost more than developing simpler rounds for a larger gun.

Thus, you're spending the money to develop a wholly new gun and wholly new ammunition to be used in that gun, but forcing yourself to be restrained by the old caliber just to take advantage of some stock of ammunition that will eventually expire anyway. Unless your nation stocked up on ammo the same way the US stocked up on Purple Hearts before the proposed invasion of Japan, the cost savings appear to be rather limited at best in comparison to the funding required to complete the rest of the project.

The utility of this gun is also rather nebulous. The US used old M68s on MGS because it didn't need anything more than legacy performance out of the old guns. Kill a few light enemy vehicles and fire off a few HE rounds to hit enemy fortifications, not kill enemy tanks. If you're deploying in support of infantry, you may very well not even need IWS levels of performance. Which in the end leaves the proposed upgrade in something of a purgatory, being a very expensive upgrade for what is supposed to be an infantry support platform designed to rely on old ammunition stocks, and insufficiently "future proof" for an actual MBT armament expected to last until 2020 based on the rate of advance in AFV technology in the late 1980s. At that time, you're also reaching the point where the gun and ammo are accounting for a decreasing proportion of the cost of an AFV, a position largely taken up by electronics and FCS instead.

[Questers]

I think the most relevant question here is, why is it so critical that legacy ammunition stockpiles be used?

Idk, it seems kind of obvious. His country acquired loads of 105mm shells and doesn't have the production facilities for 120mm ammo (also, it is the 80s.) It makes sense to opt for a 105 to fire the giant stockpile of munitions you have. It was definitely a factor for the British in Challenger series.

[The Akasha Colony]

I think the most relevant question here is, why is it so critical that legacy ammunition stockpiles be used?

Idk, it seems kind of obvious. His country acquired loads of 105mm shells and doesn't have the production facilities for 120mm ammo (also, it is the 80s.) It makes sense to opt for a 105 to fire the giant stockpile of munitions you have. It was definitely a factor for the British in Challenger series.

The British were already using the 120 mm caliber though. They already had plenty of lethality.

My question is why it's so necessary to develop a new gun, new ammo, and all of the accompanying equipment for what seems to be an MGS. An infantry support vehicle won't have a need that justifies that kind of firepower and expenditure. Conversely, it'll impart many of the same problems attributed to larger caliber guns to any tank retrofits without the same room for future growth. Using existing stockpiles makes sense when existing performance is expected, as Anemos said. It's what the US wanted out of the Stryker. But Chebucto seems to want some degree of MBT-killing firepower to last him through the oughts at least. Not against supertanks, but even by the mid 2000s, ERA and composite armor have proliferated quite a bit.

Adopting a new caliber doesn't necessarily mean simply dumping all of the old ammunition stocks either and re-gunning every vehicle with the new weapon anyway. He's already willing to add additional high-performance rounds to the inventory, and presumably take the steps necessary to ensure they aren't accidentally shipped to units equipped with legacy guns.

It seems, to me at least, to be something of a case of penny wise, pound foolish to invest all this money developing a new system in order to reuse old stocks, only for it to be either underutilized or have a reduced ability to cut it as far as expected. If Chebucto still expects to be fighting early-model T-72s sans ERA all the way to 2020, or is fine with having a gap until then, that's fine. It's admittedly hard to judge without knowing the full nature of the long-term strategic outlook.

[Rich and Corporations]

This is my Nomination. There are many like it, but this one is mine.
Nominee: The Kievan People

[Anemos Major]

Thanks for the information. It sounds like it wouldn't be as easy to use the 127mm/45s on the new platforms as I had hoped for. I had been hoping I could just shove on a new muzzle brake and an autoloader and would be good to go, but having to replace the entire barrel means that it'll still cost a fair sum, and its going to be fundamentally inferior to the later gun. Although I like the idea of keeping the 127mm/45 in service for a significantly longer period of time than otherwise, I guess it is just going to have to be shuffled off to reserve formations. 127mm/52.Mle.71M2/MBs which are the muzzle brake equipped version of the 127mm/52 will have a low enough recoil for mounting on mid sized platform, and lighter units would have trouble fitting a 127mm/45 anyway and if they do get a gun system they'll probably be of 76mm-90mm-100mm instead. The only major advantages L/45 have over L/52 as far as my guns go are decreased cost and very slightly decreased recoil, and if the cost advantage isn't there to enough of an extent to outweigh the capability loss, then I have no real reason to keep on using the L/45s. I guess just keeping them in reserve to replace worn out L/45s instead of just redoing their barrel to get rid of them will solve their presence neatly enough in time.

Well, I mean, sort of, but barrels work their way through a barrel life as well - you're going to run through existing stockpiles at some point. The great advantage of remaking your barrels is that you can achieve a fair bit with something that is, in the grand scheme of things and costs, not all that much (so long as you've retained the original machining equipment or some-such) - you can adapt the thing to use a muzzle brake efficiently, you can use whatever improvements in metallurgy that've come up between 'then' and 'now' to improve the gun overall, and you can, pursuant to the above, try lightening it for efficient use on a lighter platform.

I just need to ask - what exactly is the platform you were planning to mount the /45 on in the first place? Because my thoughts about the MCV being altered to use a 120mm down the line have been conclusively dispelled by purported TRDI simulations that point at a vehicle of that weight range with wheels requiring up to 10 wheels to keep the ground pressure down to a manageable level, which is a pretty valid point - if you're using a wheeled chassis, that's one hell of an uphill battle in development terms (and a headache for me).

The MGS fills the same role as this yes. Picture it more specifically the role of tanks in Kosovo or Afghanistan.

Righto - though 'tanks in Kosovo and Afghanistan' are a pretty wide category. Danish tanks in the former spent a bit of time as an anti-tank QRF, for one.

The RO IWS was fully capable of using old L7 munitions. There was nothing keeping it from doing so. I think you are assuming I mean to attain performance gains using the legacy munitions. Rather I am looking to gain performance gain with new munitions while maintaining the ability to use the legacy munitions.

Sure, but it's not as though the gun is going to transfer over any notable benefits in its own right, given that it's essentially built to absorb the recoil from the new APFSDS round it's meant to be firing. If you're meaning to do the latter, then it's a far cry from the MGS - you're saddling yourself with a fairly big gun designed for a new APFSDS in order to save costs by using legacy munitions.

It is, however, cheaper. The cost of the new gun is in the cost of the new tank. The cost of the new round is additional. The savings come from legacy munitions carrying over and the ability to maintain that legacy stock for use. Or, for example, to use it for reserve tanks using the legacy L7 which will only lose out on the new gun and new ammo for it.

But exactly how extensive are those savings? In a sense, you're going to be cramming money into an out-of-period technological foray in order to create a degree of commonality between the old and the new. This isn't exactly NATO, and you don't have a whole host of allies with 105mm stockpiles - between training, operations and eventual ammunition degradation, you'll run out of 105 stocks at some point, and unless you have fairly extensive stocks you, as an expeditionary geared NS nation, aren't going to last all that long in that regard. Given that this is the case, you're paying yet-additional money to increase the efficiency of the 105mm to extended levels instead of adopting a 120mm to increase lethality, which is the easier and somewhat more 'brute force' approach to the issue - towards the end of using a more-finite-than-you'd-expect supply of munitions for some period of time.

Not that this is a bad idea, mind you - there was a considerable camp in the US who believed the 105mm, and the original M1, had considerable growth potential in its ammunition alone, and there's nothing wrong about realising that. But I don't think that such a development and implementation effort would be as beneficial or straightforward as you'd like.

I'm not sure if you understand how the intent to use legacy munitions is held here. The tank is expected to hold its own against expected threats. Upon introduction this means T-72B sans ERA or less. This is perfectly.achievable in 1990 from an IWS like gun with new round. The legacy stocks come from the previous tank which used the L7, and are intended to achieve no more then their design, but their continued use is preferable.

When common threats change in the mid-late 1990s then things change. Hence a replacement project for the tank I am working out. But that is not the frame of reference here.

In which case, this is sort of fine - but you'd do best to remember that by an MT timeframe, 1985-1990 is the period where nations begin to realise that 120-25mm APFSDS is the standard to shoot for. ERA is particularly nasty in that regard, because it can be retrofitted quite easily to older designs - it doesn't take much to convert a T-72B to a T-72 with Kontakt-5, and that radically alters your threat picture. So long as you recognise that there'll be a period where your tanks are quite vulnerable, it's okay.

Idk, it seems kind of obvious. His country acquired loads of 105mm shells and doesn't have the production facilities for 120mm ammo (also, it is the 80s.) It makes sense to opt for a 105 to fire the giant stockpile of munitions you have. It was definitely a factor for the British in Challenger series.

Americans in the Abrams series...?

Sort of, but at the point at which you're considering 120mm you don't have the technological capability to squeeze that much extended performance out of your 105mm guns, I suppose - in his case, this works because his requirements are fairly modest and oddly 'expeditionary' in nature (despite having all these 105mm rounds), but if you're looking for a 1980s tank that's meant to be able to engage enemy first-line tanks into the conceivable future, this approach becomes a little bit more questionable. Hence, say, the Japanese approach -

- Does the 105mm have growth potential? Yes, sort of.
- Does the 120mm have decent performance? Yes.
- Are we going to be using this thing for a while? The MoF hopes so.
- Does the 120mm have growth potential? Absolutely, and given its current performance it'll hold out until that potential is realised.

Couple that with the usual 'oh but the Americans have it' and that's the sort of thought process you might expect in the 80s-90s. Existing stockpiles are sort of a foil to that argument, but only insofar as they're existing without requiring further production - any more than that and you might as well invest some sunk costs and turn that production to new rounds and guns, I suppose.

[Rich and Corporations]

should I give half my tanks 120mm guns, and when those get worn, rebore them to 135mm guns?