New Muslim Terror Plot in Melbourne, page-38

long or short .22? 

AR15  and M16 both can use longs. 

And what kind of bullets?

.22 can cover a huge range, it ain't just rimfires (which is what everyone bases it on). Also .22 can do some terrible damge, as some (depending on velocity) bounce around inside rather then punching through. The other end of the scale is that they only give a flesh wound.

Depending on specifics they can either bounce of your teeth, or zigzag your internals. 

Pretty sure Regan was shot with a .22 from a revolver.