i have a 115 v makita 6302 drill and the hole end of the part where u stick?

Did the whole chuck (piece that holds the bits) break off or just the screw that holds the chuck?
Here is a Makita breakdown of your power tool so you can get an idea of what your Makita 6303 looks like and the part#'s you will need for replacement.
http://www.toolsandmachinery.com/index.php?cPath=2213_2262_2263_2265
Let me know if you have any other questions.

Don- www.toolsandmachinery.com
April 2009