I have used the military pop flames, now there is some light. Single use tube of undetermined gauge. pull the top off put the top on the bottom give it a hard slap with the palm of your hand while hold it up right with the other. and they were pretty water proof.
Yes, they're kind of impressive. WP (white parachute) is good, so are RS (red star). There are a lot of others, but those are the two in the basement. When you get someone young and innocent, they're fun to fire. Really impresses them.
The OPs problem will be harder to solve. I assume he's planning on using them when he's way out and no one knows to look for him. They used to make flares for the common centerfire rifle calibers like .30-06 and .308, .30-30 etc. I haven't seen those for sale in a while. Even the little marine 12 ga solve a problem in that you can easily store 6 or more flares in a tiny space. If you've got enough of them, there's no reason to sweat one or two misfires. Penguin Industries used to make a pen gun that would take teargas or a bunch of flares. I haven't seen one of those in a while and don't even know where mine are hiding.
NATO also made a very similar but pretty rugged signal flare of the same design as Penguin. They even had "report" cartridges available. I question the legality of those. Its like a flying M80. I still have a bunch of the flare cartridges. If you can find that item, it would be the best bet I think.
Folks don't understand that FBI agents sometimes find themselves hiking straight into nowhere. Sometimes good, other times maybe bad. My brother had to investigate something involving a railroad in Wisconsin. He didn't mind and even found a train engine that had rolled over and into a ravine. Long ago. It seems crime isn't always in the city.
So consider something small and easy to carry. While more sturdy and heavy would be good for the car, the little red plastic ones are light enough to fit in a small pack and you'd never notice it.
