I use this mount on both my 590A1 and 930.
http://sjhardware.com/store/modules.php?name=catalog&file=product_info&cPath=107_127&products_id=337
I have a TLR-2 light/laser on the 590 and a Fenix TK12 in a 1" scope ring on the 930. This mount works well on the 590 since you can clamp it on the mag tube and still remove your barrel for cleaning. I'm switching to a railed handguard on the 930 since I find it annoying to have to remove the light mount whenever I remove the barrel. Probably switch to a more compact light as well, TLR-1 or X300, depending on what comes up on the EE.