I will be able to test the kantrael seriously. Finally Merk has given me a 379 kantrael shotgun with a good blessing.
This evening I will go to heresy and damnation with it.
For now, I feel that the kantrael is effective in really close combat. The special action is not, in my opinion, really something I would use a lot.
About ammo… shotguns need definitively more ammos.
I made a poll about that (and also agri / kantrael / lawbringer)