After reading a funny story by mauser66 in the reloading forum I thought to post something which has given me cause for some consideration of late.
Why is snow in the barrel a problem? Note that I'm not denying it is a problem, I'm just asking for someone to explain the mechanism by which snow causes your barrel to blow up.
The way I see it as the bullet travels down the barrel it is preceeded by extremely hot gas at approx 6,000 fps and I would have imagined that this gas would easily displace snow or the occasional drop of water or oil. However, there is no question that people have barrels blow up due to water or whatever being in there. So, does anyone know how it works?
I appreciate that if you have enough snow then the gas may not move it before some pressure builds up but I would have thought that pushing a little snow out of the barrel requires much less pressure than forcing the bullet into the rifling. Also I've seen some reports which indicate that shooting a bullet which is too big for your barrel is unlikely to cause serious problems as the pressure swages it down to fit. I would imagine, once more, that swaging a big bullet into a small hole to be much more dangerous than having a little plug of snow in the barrel, I just can't see how swaging the bullet could cause less of a pressure spike than blowing out some snow.
So, has anyone any ideas? Please note that all experiences seem to indicate that shooting a rifle with snow in the barrel is potentially fatal and a "very bad thing" so you shouldn't do it and I'm not suggesting it is safe, I'm just interested in the processes that make it "not safe."