I live in the Ozarks where humidity and hot weather reign in the summer. Over the years I have maintained my guns with WD 40 for rust prevention on their exterior and it has worked. The safe queens also have a golden rod which helps. The problem I've encountered is I can get through about 2/3 thrids of an aerosol can of WD 40 and it goes dead. I am unable to get out the rest of the product. For that reason I've quit using the product and I'm looking at other methods. I see they have WD 40 in bulk for $31 a gallon on Amazon and if I can find a reliable spray device I might go that direction. So far all the spray units I've been able to find are Chinese junk. Any ideas?