I’ve always wondered this.  Taofledermaus takes a look:

From the description:

I think most people have heard that you should never use pointed bullets in tube-fed magazines, often found on lever action rifles. There are special bullets made, with either flat noses or soft plastic tips to prevent the tip of one bullet from setting off the primer of the round in front of it. SO, we wanted to see just what it takes to actually cause a chain-reaction. Don’t try this yourself in your home!

Not the most scientific, but still convincing.  I really thought at least one of those tests would set it off.

Would I feel comfortable putting pointy bullets in a tube mag?  No, I don’t care what tests show, it just appears potentially risky.  What about you?