AH, I figured it out, wish I could edit my comment. To turn this into sandbox mode, just need to add
<script file="sandbox.lua"/>
right at the end of the main.xml file. Right after where this is currently.
<script file="main.lua"/>
I don't mean to say this should be changed, if the map creator wants it to have ammo that's fine. Just wanted to let others know if they want to play it sandbox as well.