Thanks RetroMan!
bladesinger: Cannon Fodder uses a custom save format, but the emulators I've tried to use to make the save disk with can't handle the custom disk write code. Hence (as far as I know) the only way to make one would be to create the disk on a real amiga, use transdisk, and then try the resultant ADF.
It could be that someone got lucky with the emulators, and Cannon Fodder made it's custom save disk intact. I'm not sure. As for BTTR not having it, I think someone should up it to them!
I'll do that when I get a chance.