Hi Mark
Tanks for the additional photo.
I still don't quite understand why it was called a flame Mortar. I see that it was an incendiary projectile but also that it was intended for bunkers and emplacements.
How so. What effect did it have on the concrete? I can only opine that it was an air sucker as it burned and those inside died of suffocation. Maybe it had some penetrative qualities? I dunno.
regards
D