Profile of Hannibal

Since it can stop a blob it it tracks if it used correctly. If in your opinion it not easy to use maybe you should asking for it become more player friendly instead of asking for Scott to be redesigned as a crowd control unit when it mobility and tenacity already seem to create issues.

The same way one is in trouble if one does not tech T4 as Soviet or Ostheer only it cheaper to get Captain.

No, seriously no. If that's the level of argumentation then I'd rather stop it right here.

Which units exactly would be negatively affected by a high penetration at gun? It wouldn't happen to be even bigger tanks than the p4, would it? God forbit at guns(all of them in the game) do their damned job and penetrate armor. Coh1 had shells bouncing too, but not like this. Any tank you had did not dare be on the receiving end of an at gun. Now in coh2 we have units hard countering their counter. That's not to say heavy tanks should be immediately wrecked by a 270mp weapon, but it should be good enough to at least deter the player psychologically and wreck them if they make huge mistakes(as in that video).
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Which is exactly what the 57mm does at least with the increased penetration ability. Again, you forget that 4 out of those 5 shells penetrating is the most likely outcome. And judging by the distance, the chances were actually even better. No one is going to yolo his P4 into that ATG. Even against a Tiger it should pen at least 3/5 frontally. I am not saying USF's AT design is great, because it really is not, but at least with the high penetration rounds, the 57mm is doing well. To put this into perspective: The 6 pounder (basically a clone of the PaK40), would have gotten about 3,6 penetrations in a similar situation.

Then make it an Ostheer P4, is it so bad that we prefer having a tank that has no reliable counter on USF roster except for the Jackson?

It would solve the issue for the P4 for sure, but not for the JP4 or Panther (or even Brummbar against OST for that matter). I don't think the OKW P4 by itself is really an issue since it fits the faction's design as well as the overall balance. It is just USF's shitty AT design of having no high pen unit apart from the Jackson or the option to constantly churn out munitions. USF's current design is relying on a lot of lower chance RNG rolls instead of fewer high chance ones. This can lead to the shitty RNG you got here. Your ATG could have penetrated 4 times in a row even without the high pen rounds. This scenario is about 100 times more likely than what you got in your video. Should the OKW player be able to make a post claiming that this shitty 270 MP ATG regularly wrecks his premium medium?
That's why people are saying you only got an example of bad RNG. But to be honest I'd like to detach from the example video since it does more harm than good to this discussion.

I think what would be good to clarify is what you actually want to argue about:
- Should the 75mm have higher base penetration?
- Should the ability be better?
- Should the OKW P4 have lower armor?

Again, all of these can be argued about for sure, but all of them will probably come with more changes than just changing 1 or 2 stat values in the editor. And most likely also at a price for USF, because (unlike the Jackson armor nerf), all of these changes have larger effects outside of the interaction between the 57mm and the OKW P4.

Ok, I'll take your argumentation, so the best Atgun in game can bounce 4 times in a row vs a medium tank. You're just making the P4j smelling OPness with such argumentation.
Then about its timing, if that was a relevant argument then the Ostheer version should be the worst medium tank since its the first hitting the field in any condition.

As much as tank destroyer shouldn't survive if catch off guard, medium tank should have the same treatment, I catch it off-guard and had time to fire 5 times, same issue same outcome should be made.

What's your solution then?
Lowering P4Js armor? The unit is fairly balanced for cost and timing itself (at least in my opinion), so the only way that should work is with a simultaneous cost decrease. Which would basically make it an Ostheer P4.
Increasing the 51mm penetration? Screws over other targets as well.
Increase the ability's pen gain? Basically same as above.

Look, I've been arguing for redesigning USF's AT options including the ATG for long now because in my opinion the current system only forces USF into a Jackson.
The biggest difference to the situation P4 vs Jackson is also the scope of the changes: Making the Jacksons thin armor a little bit thinner is in line with the unit and almost exclusively affects the P4 and the Puma. The armor nerf was done to ensure that good positional play is important and finding someone out of position is rewarded.
Should you have been rewarded in your video? Yes, surely. But changing any of these two units to guarantee the penetration changes way more than just those two units.

I have not played the Scott a lot recently, but in my eyes the Scott must be good at auto fire while PaK Howie and the mortar are barrage units. Potentially even remove the barrage from the Scott if necessary. The Scott has to be the late game bleed unit that USF otherwise only has in the Calliope.

I think your wish has been indirectly granted since this is likely the last patch CoH2 will get