That was a terrible game of "russian roulette" to play with such a nice lantaka.
I always feel a bit terrified when people fire lantakas very casually, like they were some newly made steel ones. I have nothing against firing original pieces, I hope to do that when I "grow old", but only if you know what you're doing and you know that the piece can handle the firing. Lantakas are so obscure in their origins and manufacture methods that I wouldn't ever fire one.
If that one really came from the Bannerman Arsenal, it must've been captured during the Moro Campaigns and should be in a museum or in some appreciating collectors hands, not used for dangerous games that might leave the gun destroyed and the player dead.