I was not going to mention why not to use WD again but Randy just gave you the exact reason not to use it. I know the guy that got it working for you recommended it but it is a very poor lubricant, its not what its is designed to do. The liquid graphite is probably the best for locks. And don't forget the inner claw.
As I said earlier... Dry slide has a 3" needle to get to the bottom pin. It is mostly graphite with a carrier solvent that evaporates. Spray WD-40 on a piece of cardboard and come back in 15 minutes and see what you have left. Mostly nothing! The solvent evaporates and leaves very little lubricant. Thats why the locksmith told you to do it every month. Try the graphite based products and you will only have to do it once a year.
Lot of guys using it on weapons too. http://www.amazon.com/Bike-Dri-Slid...UTF8&qid=1403107269&sr=8-1&keywords=dri-slide http://www.uniquetek.com/site/696296/product/T1247