CombatArmsUSAF: My most recent PCS was OCONUS and I was in the same boat. I asked the same questions, did a lot of searches, and eventually arrived at my own successful solution.
1. Remove any wood/antler stocks or grips and store separately.
2. Weapons are slathered with a heavy coat of normal gun oil (your choice: CLP, Rem Oil, RIG Grease, etc). Dissassemble and coat main parts (slides, frame, reciver, barrels, etc.). Applying oil with a shaving brush or small soft paint brush will get the oil into crevices, rails, triggers, hammers, etc.. Not enough to drip off of the weapon but enough to give a "wet" appearance. Don't forget to liberally coat interior of barrels.
3. Handguns go into silicon impregnated gun sock (available at most gun shops, online, or WalMart), then into pistol sized vapor barrier protection bags. Throw in a couple of vapor inhibitor chips. Seal by folding or tape.
4. Rifles/Shotguns into silicon impregnated gun sleeve and the long gun size vapor barrier bags. Throw in chips. Seal by folding or tape.
5. Leave them with your trusted agent and give that person instructions to store weapons in a dry room temperature location (not an attic; not a damp basement). Have person agree not to break seals on stored bags or take weapons in and out of storage configuration.
The vapor barrier bags I bought were opaque red in color (Kleenbore Products?) and I got them from Midway or Brownells for a coupla bucks apiece (forgot which). They are 100% impermeable to water vapor and impregnated with some sort of chemical protectant. Do not use commercial ziplocs or such...they will allow in microscopic amounts of humidity.
The links below show some of these products from Brownells.
http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=1207&title=RUST-BLOX+VAPOR+TABS
http://www.brownells.com/aspx/ns/st...1154&title=TRIPLE+TOUGH? PREMIUM STORAGE BAGS
http://www.brownells.com/aspx/ns/st...850&title=BORE+STORES+LONG+TERM+STORAGE+CASES
Years ago I had an oiled commercial M-1 carbine get seriously rusted sitting in a footlocker in a basement for 3 years.
Nowdays, I go overboard: Oil, Silicon Sleeve/Sock, Vapor Inhibitor Chips, and Vapor Barrier Bags. Weapons were absolutely fine after 2+ years and I suspect would have been good to go for another 8 years.
BTW: I stuck a last minute Mossberg 500 into a vapor barrier bag with a light coat of oil (no silicone sleeve or inhibitor chips); I just pressed as much air out of the vapor bag as possible and roll- folded the top without sealing it with tape. It also survived my absence without any rust.
Don't store any weapons with bare metal contacting foam (like in a plastic pistol case) or non-impregnated cloth (like a pistol rug or blanket). These materials will absorb and hold small amounts of water vapor from the air and cause rust where they touch the weapon.
Do not use WD-40 as it will evaporate and not provide any long term rust protection.
Small parts (or even entire weapons) can be put into wide-mouth, screw-top, liquid-tight plastic toiletry or kitchen containers, and immersed with oil. Cheapest would be to get something like a large shatterproof nalgene bottle and a can or two of Mobil One Synthetic Engine Oil (which works as well as any gun oil).
In any event, I had great results with oil and vapor barrier bags (which is how the Army currently ships/long-term stores its weapons).
Good luck...
