From a post to Baen's Bar BuShips dated January 20, 2002:
Warp point denial II
If the defense [using a railgun to fire a stream of iron slugs
into the warp point - Ed] were allowed -- which it isn't -- there'd be no need to use
a rail gun; just dropping in the garbage Arnold suggested in his original post would do
the job. Unfortunately, you can dump stuff through a warp home till the cows come home and
it will have absolutely no effect on ships (or objects) transiting in the opposite
direction. Which means that any defense based on obstructing a warp point, or shoving
stuff through it, is going to be ineffectual. In short, this won't work.