Obsidian Spear Rifle

A thought occurred to me: Pistons provide spring power to propel projectiles. Gunpowder does the same. What happens if you combine the two? The result of this thought is the Obsidian Spear Rifle:

The combined power requires a structurally sound device.

In fact, the propelling power is so strong that only obsidian is tough enough to not completely shatter upon firing. (Merely break into spear-like shards, which I consider a nice bonus.) The interesting side effect is not only the decent damage but also the Wither effect, bypassing regular armor. Unfortunately this comes with a bit of a cooldown after each shot.

I have yet to make the reloading mechanism more efficient, but for now this will do.

Note: The reloading mechanism has been greatly improved, by making use of Obsidian Magazines. This also improves the weapon’s ammo capacity to 16.