Considering it didn’t reach mass production, it could be an event or premium tank. It’s very comparable to the Sherman 105, has a longer reload time, but has AP ammo instead. So I’ll put it in BR3. (It’ll definitely be easier to destroy than the Sherman)
According to WT it has a reload time of at least 16 seconds. It is worse than the Sherman 105 in every way.
(The Sherman 105 doesn’t even need AP shells, it’s one of the only BR3 tanks that can easily take out a Panther from the front.)
Sherman 105? yes, it can easily take out a Panther from the front. Not sure about the Tiger H1, I rarely see them.
And if you mean the KV2 (Zis 6), it should be able to destroy the Panther, but it definitely can’t stand up to the BR5.
The Kv1 and kv2 are already near impossible to take out as infantry as det packs only put a dent into the treads at most. I say put it at br4 as the kv2 is already up there for a reason