Thanks!
The barrel is generally 4.5 feet long, though it can detach into smaller pieces for testing. The tank itself is short and wide, so its more then 2 feet in the oppisite direction of the fire. I thought decompression might chill the barrel, but for now it leaks so fast through the damn compression fittings its not noticable.
Range is limited. For now, maybe 4 feet at best. The orginal model a coworker at Pizza Hut showed me could torch things from more then the lenght of a dumpster. I'll be happy if the finished device can light brush/sticks/whatever from 10 or 12 feet.
Backup: I have a 1/8 barb inside the barrel that should create enough restriction, but I don't think its really needed. The tank is pure Propane, without O2 it can't burn. As long as its pressurized, no O2 can go up the tank. Also the tank is really heavily made. It was intended for combat afterall, so I'm guessing the fittings would explode releasing the blast rather then the tank. Hopefully thats not an issue though
Anyway this is still far from finished. It leaks gas like heck and can barely charge. Unfortunately I have little time to fix it now. But anyway, heres a quick pic so you know I'm not BSing.
Once I get the bugs worked out and think its (reasonably) safe I'll probably do a quick writeup and post more pics.