Tim,
See VERY rough sketch :

Tim
This is my "rollertowel". To make it you need a length of towelling about 550mm wide and 1200mm long, and some soft clear plastic about 550x600mm. The plastic panel is sewn onto both ends of the towelling to complete the loop. I then lay the clear panel centrally over the scope, and the towelling goes underneath the rifle and rest joystick and out to the right hand side where the ammo box is kept dry in it. The 550mm width should allow it to come back over your eye-piece while extending forward past your objective lens to keep that dry too. The total effect is to keep your breech, ammo box, and importantly loading hand dry throughout the shoot. The clear plastic allows the RO to see your action which is important, and keeps your scope knobs illuminated.
I checked with the CRO at the Nationals and he allowed it, and if it is the same ("SOB"

) RO at the QRA Queens then I'm sure it will be allowed again. Firstly he didn't think it was in obvious disagreement with the rules, and secondly he rightly see's wet ammunition as a safety issue particularly in F-Open and F/TR where chamber pressures can be very high.
So nip down to Spotlight to get the stuff, and they serve blokes really quickly because they look so awkward.
Alan

PS. Have another small towel with you e.g. to wipe the muzzle before you start.