Any good namebrand handgun should do the job well.
I would go with a 9mm with FMJ because in my mind the slight taper to the 9mm cartridge combined with the FMJ shape would make it damn near jam proof.
I would go with a SIG or a CZ, either would do. I have one of each, and their performances have been stellar. Never had a jam with the CZ, and only one with the SIG, which was a stovepipe caused by one of my early, weak handloads that wouldn't cycle the action.
I would stay away from a Kimber, because there is no excuse for making a $900 handgun that won't perform as well as a $300 one.
I would also think that a revolver of .357 persuasion would work about as well as anything could. But I would prefer an automatic though, because in my experience the sights are generally better regulated on an auto.
If rifles were included, I would choose an AK. Despite any differences that anyone may have with them, they are about as prone to work reliably as any weapon ever could be.
I would also hope that the gun store carried cannon fuse. I would need a length of it, a pound of black powder and some bullets or shot.
If the gun didn't work, there are few things that would withstand a good field expedient explosive device.
"You wanna be a suicide bomber, huh?"
"Let me help you with that."