To be fair, he was running 20x mixes. Though, I have noticed the breech of my barrel has melted very slightly at where it glues in to the threaded adapter.
Actually, I was only running a 10X mix when the barrel melted, if I recall correctly. However, I was using a 4" diameter, 2.5L chamber. There had never been a problem when using the "normal" chamber, which was 2" diameter and a litre or so. Softening won't be an issue here. Any "reasonably" dimensioned pipe will explode in these conditions long before it melts as badly as mine did (remember, mine's was 1.6" ID, with 1" walls composed mostly of resin bonded glass fibres). As to repeated damage from the heating cycles, I can't offer a useful opinion there; I never ran a barrel through enough cycles to notice those effects.
I'm well acquainted with your problem in barrel choice, Crowley. It was what drove me to that reinforced plastic barrel in the first place, which ended up disappearing in a $200 puff of black smoke when I increased the chamber volume. There's no easy solution for most of us without ordering online. The best I can do is recommend a fibreglass reinforced DWV copper tube barrel (the tube itself is generally rated to 200-300psi). Weight concerns would probably prevent you from using a seamless steel pipe barrel like I did on the CGG-50, even if you could acquire one.
I've also pushed one ABS barrel to the point that it failed from overpressure alone. As one would expect, it did not shatter or throw fragments. It would, however, have caused significant injury to anyone standing near the breech, much less holding onto it while it was fired. Think of the effects of removing the barrel, and holding your arm in front of the burst disk while pulling the trigger - that's essentially what vents out the rip in a failing barrel.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
). Aluminum would also be nice, just keep in mind that DOM isn't actually intended for use in pressure vessels in most cases. Leave a generous safety factor and do some higher pressure remote testing if you do end up using a non-rated barrel.
