Well, not full on muskets.
The musket arena is finished and has been released; it's near football.
Currently there are a few bugs in the arena level that are being fixed by Excalibur. If you come across any other bugs, just report them to staff and they'll be fixed as soon as possible.
I have to converse with the musket staff, because I hope to make the musket a buildable item, which will require many separate jobs and items to create, and variations of the musket, and ammo creation and such.
But we'll have to see.
For now, go to the arena (again, it's near football), and go have some fun.
Make sure to bring an Events Team member along, though!