Blowguns... *shakes head*

Every culture that I'm aware of that has used the blowgun has used poison darts. Without that, you've stabbed them with something like a hat pin if your tube is skinny and short enough to be mistaken for a trekking pole. And not stabbed them very deep.

A good blowgun is BIG- six feet or so in length, and fires something about the size of a chopstick. But it is still SLOW, with very limited range.

You are at least as well off with a pocket full of steel balls and a good pitching arm.