ORIGINAL: biscuit jake Reading various links about the high pressure, fast, short & fat cartridges: I read one that said you can get to the point where the pressure is so hot, it starts to melt barrel. (Thus shortening barrel life & causing erosion.) So, if this is right... what kind of pressures start to take us into the barrel-eating category?
Back in the 220 Swift days, barrels had shorter lives but that was due to velocity, I understand. (Never owned one, tho)
Your understanding is slightly incorrect. What "wears out" the barrels of high-velocity rifles is NOT FRICTION from bullets, but eating away of steel due to the temperatures of the high-pressure gases melting and carrying away barrel steel every time the gun is fired. The more powder you burn, the higher the pressures are, and the longer the peak pressures/temperatures are maintained, the more steel is cut away at each shot.
ALL high-pressure smokeless powder loads wear out barrels this way! But cases that hold more powder in a given bore size, which produce higher velocities and higher sustained temperatures do it more than ones with smaller charges. This is why the .220 Swift ruined barrels in a relatively few rounds. Additionally, people who insist on firing so fast you can fry an egg on their barrels, regardless of the size of their cartridges, are doing their best to keep barrel makers in business.