I use the Aim Field Sports drag bag which has lots of pockets, padding, place to put cleaning rod and a good harness for carrying hands free.
However I only use it when on the target range as it is too big to carry when out stalking and also too fiddly to get the rifle out in a hurry.
For use on the range it is brilliant as it holds a lot of gear and makes life at lot easier for moving to/from the firing points.
Mulac