When downloading a SNAPSHOT-version from artifactory (current release) there is no cache-control in the headers set. Hence Firefox caches the file for some time and you will not be able to download updated versions with it. (I think the firefox-behavior is stupid, but artifactory should get it right nevertheless)
Snapshots should not be cached because they could change anytime in most setups. So I suggest adding a no-cache-header to this download. Releases on the other hand could set a long TTL for caches because they should never (rarly?) change.
(A nice feature would be to support etags and not-modified-since to minimize traffic)
Current http-headers as send by artifactory:
HTTP/1.1 200 OK
Last-Modified: Tue, 21 Jul 2009 20:24:39 GMT