Don't bunch up your M10s

[Amizaur]

The slow-down would depend on amount of armor that was penetrated. If a Tiger I round, with penetration potential of about 150mm RHA from close range hits a 40mm plate of armour, it would not slow down very mucb after penetrating it. The thin plate, falling critically, would not take much energy from it. Let's assume the shell was going about 750m/s when it hit the first armor, with penetration potential about 140mm of RHA. That would be about 300m range. Penetrating an overmatched thin plate would require less than "40mm" of it's potential - several close-spaced thin plates are not offereing the same resistance as single thick plate of the same overall thickness. Let's assume assume the shell "lost" about 30mm of penetration potential after that. So right after penetration, it has about 110mm of penetration potential left. What velocity would that be ? 110mm of penetration a Tiger I shell has at about 1500m. It retains there about 640m/s. So the slow-down was from 750 to 640m/s after penetrating 30-40mm of armor. Now the burster detonates, taking away 1/3 to 1/2 of shell mass. How would this affect penetration ? I guess it would be severly degraded, maybe even halved (the shell cross-section density was severly degraded), so we got about 60-80mm of penetration potential remaining, maybe more, maybe less, depends if the shell is tumbling. Now the shell has to get out of the tank, it won't have much left after that. But still can penetrate a halftruck parked right after the tank.

If the shell was undamaged, I mean fuse didn't work, or the armor penetrated was too thin to trigger it - like 10-15mm - there is another story, full 110mm of penetration left or more (in case of 10mm of armor, less than 10mm would be "taken away" from shell penetration potential, full 140mm still left, and the slow-down would be minimal), and still 70-80mm of penetration left after leaving the tank trough the second armor - so it can still easily kill another one trough another 40mm of side armor.

As for trajectory change - all depends on hit angles. If the hit was at angle, the shell would change it's trajectory a little (against thin armor) or more (against medium armor). If the hit was perpendicular, from 90deg side angle - there would be almost no change in trajectory, the forces are symmetrical.