Verified answer

Is your sentry gun safe one of those tin boxes for sale at Wal Mart? If so, your guns will be rusted junk and the ammo not in much better shape.

Your enemy here is moisture. Your safe will have to provide a dry climate for your arsenal to survive. I have a damn expensive and well built Liberty safe and I am fortunate to live in a dry area (Wyoming). But I still have to check, clean, and oil the guns I do not shoot at least every six months.

If you store your ammo in GI style ammo cans, they will easily last your 20 year term

If you load the mags and leave them for that long, you may run into spring fatigue and they will be weak.

Assuming you store the rifles and shotguns standing on their butt stocks, the recoil pads (if any are installed) will probably collapse.

The metal of the guns will develop "storage marks". wear marks on the metal were it rests against the long gun rack or on the side of the guns in contact with the carpeted shelves the guns are on.

And, finally, the lock on the safe itself may just rust shut.

Your hard and soft cases are not for long term storage. For long term storage I would get a safe. There are many safes out there from as little as $150 all the way up to $10000. I have a Timber Ridge made by Liberty for Gander Mtn. It weighs in at 900 pounds and has a 45 min fire rating. If you store firearms in hard or soft cases you are going to get rust no matter what you do. Some will say to get a gun cabinet. I now shy away from them because they are like a smash and grab showcase for a thief. If you want many local PD or sheriff departments will give you a gun lock for free for all of your guns. I am one person who does not like them as they cause more damage to the firearms than protection. Trigger locks are not that good either. I have taken floor plates off and had access to the trigger with a trigger lock on. Stack on makes metal gun lockers that work and can be bolted to the floor and wall rather easily these are a cost affective way to store your firearms. You can stick it in the far back corner of the closet and no one will ever know it is there unless you tell them. If you are going to use this modle I would get gun soks for them that way you do not bank up the finish or the metal or wood.

No.

first although most magazine springs of modern manufacture will not take a "set" if left loaded over a period of up to a year in some cases, 20 years will destroy them and the ammo will not feed.

Second, it depends on the climate control of the inside of the safe. Moisture from the air can condense and cause rust on firearms left untreated properly for storage. You would need to clean all lube etc off them, and cover them with a military grade cosmoline, inside and out, to protect them long term, or be able to enter the safe once a month and wipe them down with Breakfree clp or similar product.

So, you would need to place the ammo in proper storage containers, with desiccant inside, and then yes, it would last 20 years if the temps were maintained in the mild range. The firearms coated in cosmoline and left with no tension of the springs etc will last just fine, and the magazines would also be fine if treated the same way and left unloaded.

shoot safe

I agree with Mac. I own 6 gun safes, so I think I know a little about how they work - and don't work.

Depending on the climate where you live, you will need a means to keep the moisture out of the safe. If you can, install what they call a "golden rod", which is a heating element that you place in your safe and it attachs to a standard 110 volt power cord. This "rod" get rather hot, maybe to 160 F or so. The idea is to keep it warm enough in the safe to always be keeping condensation from forming.

Another thing to use are silica gel packages. Get the largest one possible. In fact, get two of them. These will suck-up any aditional humidity inside your safe.

Believe me, I have a tough time maintaining my safes to keep the rust off of my firearms. Because of weight issues with the safes, I have to keep 4 of the larger ones in my basement - where it gets rather humid. So, every month I am "baking" the silica gel packages to allow them to again suck the humidity out of the air.

Moisture, humidity - they are the culprets!

If you just put a normal coat of oil on the guns, they most probably are going to rust. You would need some method of removing moisture from the safe or pack the guns in grease. If you pack them in grease, they would have to be unloaded and cleaned before use. The ammo would probably be best stored outside the safe where air can circulate around it if it is in a semi-controlled environment like a house that someone is living in. All of the springs would be ok. You might be able to find a safe that is truly sealed and put some desiccant in the safe and keep things from rusting. If the lock didn't leak air, you might be able to seal the safe with duct tape or something similar to prevent moisture from migrating into the safe.

If you could absolutely guarantee that you removed all moisture from the safe then sealed it perfectly, then it probably would be in the same shape. Problem is it is almost impossible to do. Other than that, its a good idea to pack the guns in heavy grease.

Well, all thats not gonna fit in a sentry gun safe. You question is unanswerable as there are too many variables. in theory, sure it should be fine. The shotgun shells might dry out and split the plastic.

The springs in the magazines would likely lose thier memory and cease to be springs

The rest of the ammo should be fine.

I would think the big factor here would be humidity. If you live in an area with low humidity, I would feel comfortable saying yes, 20 years later, they'll be ready to go.

So you're one of the complete idiots who's buying up all the ammunition?

You know you're going to end up with a Federal law against that? The right wing is going to bring down the roof on us all with their terrified gun and ammo buying!