I have further information and estimation on high caliber APFSDS for western tanks.
Firstly a secondary source (Armed Forces International Journal, February 1987). Among the several figures claimed there for protection or penetration estimated for various tanks and ammunition, theres the “XM946” identified there as a 120mm APFSDS.
Given the context of the overall article and time period, I think this is a case of misidentification for the 140mm APFSDS XM964. The confusion is plausible when the same gun can fire 120mm rounds. In any case, “900mm” for XM964 is plausible given the dimention limits of the projectile (its not that much bigger than 120mm ammunition). While dimensions of the projectile can be estimated from pictures (mostly projectile width), velocity and length can be dialed up and down to get to the stated 900mm of penetration.
Regarding Rheinmetall´s 130mm caliber so far we´ve only seen a mockup that looks a lot like an upscaled 120mm DM53. Its even more likelier that the actual first real APFSDS in this caliber will be based on DM83, which is a projectile we haven´t even seen yet (but I suspect its going to be in the 850mm ballpark of penetration). This said, I´ve estimated an upscaled DM53 to 130mm with the best velocity possible and here are the results:
980mm of penetration assuming 1950m/s (basically this is almost the maximum possible velocity for APFSDS using traditional explosive propellants, me personally I would assume a velocity a little bit lower, perhaps 1800m/s, which would produce 920mm of penetration)
I repeat, 130mm “DM13” most likely WILL NOT be based on DM53 so this is just an excersize in creativity, validating a potential penetration of high 900s mm. An even bigger projectile (length limit of whole rounds for calibers considered for MGCS is 1300mm) is more than possible so theres a lot of growth potential left.
Lastly, Nexter´s 140mm “Ascalon”. This caliber is competing against Rh130 and intended to fullfil the same requirements in terms of volume and performance. However the concepts published by Nexter show a radically new APFSDS with much higher L-D ratio (nowadays 30:1 is the norm). A secondary source states that muzzle velocity is somewhere between 1700-1800 m/s and likely its very similar to what the 130mm is required in order to hit reliably moving targets out to 4-5km.
As for the penetrator´s dimensions we are looking at something like this:
As for penetration, this projectile (934x24mm) at 1800 m/s penetrates 1050mm and at 1700 m/s, 995mm. This is pretty much equal to the Grifel 152mm APFSDS at both high and low estimations.
It’s a rough estimate from different sources, however it very well could probably reach speeds up to 1,800m/s. Perhaps I’ll gather my sources and list them under each vehicle in the future.
The Chally 130 is technically German as well, as it was tested and built there. Rheinmetall wanted a testbed to house a 130mm cannon, a direct competitor to Nexter’s 140mm, meant for the German market. Since the Challenger is wider than the Leopard it made it easier on their end when it came to installation. The British had no direct involvement in the effort.
I have some more information on the German/Swiss 140mm prototypes. The Swiss 140mm had a 1000mm long APFSDS with a muzzle velocity (MV) of 1800m/s or 1900m/s. Using some pixel measurements, we find a diameter of approximately 30mm, which (depending on density) gives us a penetration number ranging from 970mm to 1065mm at 0°. Other than that slight correction, I have little to add.
Afaik U.S., U.K., France and Germany followed a list of harmonized parameters for their 140mm guns, so their performance should be more or less equal. If i’m not mistaken U.S., France and U.K. used DU for their penetrator while Germany used tungsten. All 140mm guns designed under the agreement shared the same chamber volume of 20L and barrel length (L/48).
According to this page of the Block III/ATAC System brochure, the XM964 penetrator is about the same length as the whole forward part of the 2 piece round which is ~1m long.
That image doesn’t show XM964, but it shows the British made 140mm APFSDS next to their 120mm APFSDS, which was planned to be used for Britain’s FMBT project during the 80’s. For some reason a lot of people fell for some reddit post saying it is the XM964, but it isn’t. It’s even currently stored in Britain, alongside it’s British made 140mm cannon, which was meant to be carried on the Evolutionary National Tank
