Early Tiger 2 and Panther: The lower part of the gun mantlet and curved turret armoured plates acted as shot traps by deflecting incoming shots downwards towards the hull roof (16-17mm thick on the Panther, 40mm on the Tiger II), or into the turret ring where the shell could potentially jam the traverse mechanism. On the Panther a new flat "chin" on the mantlet solved the problem. The Tiger II production turret did not feature the curved front of the early turret, instead using a flat 180mm plate sloped back 10 degrees from the vertical. The model depicted (with the curved mantlet) seems to be fitted with a much smaller gun than the 8.8 cm KwK 43? Shot trap - Wikipedia
Tiger 'trap' snap mit shot strikes unrestored. This hit jammed the turret, but it's highly debatable it was the main reason for abandonment. All a bit moot, though, this 'dreadful/obvious shot trap' business. Yes, they became known, and yes gunners were encouraged to aim for them, but what's the alternative? Every tank a kugelpanzer? You could (and they did) mitigate with placement of barriers and deflectors, or avoiding traps in the first place (which might seriously hinder the shape of your machine), but even the smoothest modern vehicles have little corners and holes. (Though I suppose with a move from hardened full-calibre shells to saboted spikes and shaped charge stuff the very issue of deflection becomes lessened.) More WW2 traps will come to mind. The T35 was probably one big shell-catcher...
I'm more interested in the known ones rather than a solution (or not) for them. Bonus points for hitting one.
To expand on my previous post...sorry, was posting from a cell. The Porsche mantlet was rather small, but the under side of the whole turret from was curved, so as to deflect any incoming shell into the much thinner top armor. The Henschel turret did away with this curved underside & mantlet, by going with a flat, but slightly angled surface, and using a saukopf instead of a mantlet. The Panther had a similar shot trap throughout most of it's life with it's curved gun mantlet. However, with most of the G model production, this was cured with the addition of a "chin." The M-26 Pershing also had a nice mantlet shot trap, but the tank was little used, and I don't think the Germans noticed. The KV-1 also had many shot traps, although not in the way that Opana is thinking... There are several shell trapped in that armor. I was looking for that shot of a Tiger I with a soviet shell sticking out of it's front armor, but was unable to locate it on the net, so I used the KV-1.
Takao, I did edit the earlier post. Merkava's have a shot trap under the turret. It is a difficult shot. They hang chains off the turret to detonate projectiles prior to impacting the turret or hull. Photo by: Zachi Evenor Merkava - Wikipedia
The A9 Cruisers had a certain shot-trap notoriety. Those (hugely troublesome) MG turrets were almost designed to funnel shot into thinner armour around them - and the driver's head...: Same can be said for most auxiliary turret designs. Turret usually hardened, so bounces onto less solid surroundings more likely. On the 'phew - didn't make it to battle' front, The A38 Valiant ("The worst tank ever made" ~ its Bovington information board) may deserve some prizes. While boldly toying with sloped armour, its designers seem to have set every slope to guide deflections into more vulnerable areas, the very definition of shot trap, and that massive turret appears to have the express intention of sending everything into the hull. (Note the glorious placement of that driver's hatch. Thankfully the thing was only built in mild steel before rejection, even more thankfully it survives to this day, and makes me smile whenever I see it.)
From my understanding, the trap was at the rear of the turret on the early Merkavas, which was redesigned to eliminate it. The chains are meant to trigger HEAT rounds early, and will have no effect on APFSDS rounds. Thus, they are not part of the shot trap solution.