Recently I tried out Kruber with a blunderbuss because I thought it might be useful against armored infantry. However, when an actual encounter happened, after the 1st shot the squad was in my face and the blunderbuss refused to reload until the encounter ended, i.e., the squad was defeated.
So I continued with the blunderbuss to see if I could reproduce the bug. On another mission, a warpfire thrower was partially hidden so my 1st shot did not kill it. Next moment, it was in my face and although I could have killed it with my eyes shut, again the blunderbuss refused to reload until the encounter ended, i.e., one of the bots killed it.