Originally Posted by
gloob
I'm not sure why paper doesn't burn or at least scorch in a spots along the rifling marks (The rifling lines are where I suspect gas leaks to occur). Either it takes longer for that to happen to paper? Or maybe paper is a better gasket material than copper or aluminum, able to maintain a perfect seal the entire length of the barrel?
The reason that the case isn't as hot coming out of a lever rifle is easy. That's because it's in the relatively cooler chamber for a lot longer than the cases flying out of a semiauto. The heat from the case gets transferred to the chamber for as long as it takes for you to work the lever after firing it, versus the few milliseconds the case stays in the chamber in a semiauto.
I have made the observation that the cases fired out of my Glock come out hotter (read are more painful when they go in my shirt) than the ones out of my FN, and that the FN slide gets noticeably hotter than my Glock after firing a couple mags. And if you examine the point where the case gets extracted, the Glock spits them out after about half the slide travel as the FN. So the case is presumably in the chamber for significantly longer, in the FN. I have also noticed that a batch of hot S&B ammo that caused sticky extraction in my Glock was no problem in the FN, presumably for that reason. You really think the cases get heated up from the friction of extraction after the powder just went off at 2000 degrees and 30k+ psi? One of the problems the military has faced with caseless ammo is that the barrel/chambers overheat much faster, without the case to carry away much of that heat.
Regarding boolits getting annealed, I didn't make that claim, and I agree with you. It doesn't sound very realistic to me. Unless maybe you're trying to shoot boolits in a Whisper at 4000 fps. I read that the bullet manufacturers had to develop a jacketed bullet that didn't explode in a spray of molten lead, immediately after exiting the barrel. But in typical boolits at typical pressures and speeds, the boolit isn't in danger of entirely melting. It has too much mass. The surface of the boolit is a different story, due to the poor thermal conductivity of lead.