I ran across a new sound library on ebay - http://cgi.ebay.com/ws/eBayISAPI.dll...329043328&rd=1
The Guns Sound Effect library "offers a varied selection of pistols, revolvers, rifles, shotguns and automatic weapons of many different calibers...."
"Choose from more than 60 different guns, rocket launchers and hand grenades. This library includes North American and European models, vintage black powder guns, World War I and modern weapons, and full size military munitions ... plus more than 700 foley effects."
There's even an audio example on the ebay listing.
Now why didn't I think of that?
Bidding starts at $250. May be more BANG for your dollar than GPO - but what a blast you can have playing it for your frineds and neighbors.