Terry,

Before you get too carried away, you might look into the weight of 2500 rds
of 7.62mm.  The rate of fire of the marvelous GE M-134 is pretty high and to
do any serious work you need to have a big stash.  I had the opportunity
long ago in a place far away to diddle with these air toys.  Very impressive
but not suitable for use in your vanagon.  They could track you easily by
the heavy trail of brass and we know you wouldn't like that.

Sooo. stick to a more suitable stick, street sweeper with at drum.

p