Good or bad idea?

What's the point?  I have lots of old powder from the 80's that's been stored in an outside storage shed and it's still good.

If the freezer is the locking type it could  create a bomb like situation if it were to catch fire.  If the door can open easily when the pressure on the inside slightly exceeds atmospheric, then that is not a problem.  There are some advantages to storing in a working freezer.  First, it is quite a nice, though not perfect, fire resistant place.  It is cool and dry (which is ideal for storage).  It will slow any decomposition to a mere crawl (which as pointed out above is quite slow to begin with).  However, when you take the canister out on a humid day, it will form condensation on the outside.  This is not a problem with plastic cans, but will be a bit of a problem with older cardboard and steel cans.

You will want the canister to warm up to room temp before opening it, to prevent condensation from forming on the inside.   Other than that, there are no real downsides, except taking up space where your game meat should go.

There would be no realistic gain, and it could conceivably cause a major issue in the event of a fire.

Dry environment

The Humidity down here is crazy.

I'm in SC.  Plenty of of humidity here. Hasn't been an issue for me.  But I guess it couldn't hurt as long as the door isn't locked or obstructed creating a bomb.

Why? Sounds like a bad idea to me.

I would vote bad idea

If you get it cold enough, when it comes up to room temp, condonstation will be all over the container.

I don’t want any of my reloading stuff wet.

An unquestionably bad idea.

All air - including the air inside your gun powder container - contains some moisture.  Put it in the freezer and that moisture will condense onto the powder.  Contemporary powder containers are plastic of type and thickness that allows for moisture to pass through (very slowly, but it does happen).  So, in time there will be a build-up of ice inside your powder container.  Look at something you have left in a ziploc bag in a freezer for some months; note the ice that wasn't there when you put it in the freezer?  Freezers that a frequently opened make the problem worse by allowing the entry of moist air when the door is open.  Frost-free freezers make the problem even worse because they go through defrost cycles that uses a heater to melt the frost from the evaporator changing the temperature in the freezer.  Most of the melted water drains out, but not all.  That remainder then circulates inside your freezer waiting to get through the walls of your powder container.

The fact that if the freezer door has a latch, it becomes a potential bomb has already been raised.

Bad.

Bad idea, due to the condensation problem.

Like one poster said, ''I don't want water anywhere near my reloading stuff''.

Cool, dry place...a freezer is neither.

Interior closet shelf... worst case, in event of fire, all it would do is "FIZZ" till it burn out,, and home interior pretty constant for environment in house

I have some powder and primers that I recently put in long-term storage. What I did was get a high-quality large plastic storage bucket. Then I bought a large desiccator canister off of Amazon and placed it inside along with the powder and primers. Then finally I sealed around the lid seams with duct tape to help keep out any additional moisture. I am sure it is not 100% sealed, but it is pretty dang close. The desiccator canister has a large capacity, so I am not too worried, but in a year or so I will probably open it again and bake the desiccant dry again.

What about using a freezer that is not working?  Would that be a good air tight container?

It comes in an air tight container !
Don’t over think. A cool dry place.

A freezer that doesn't work is better than nothing, but I wouldn't run out and buy one or even take one from someone giving it away unless you absolutely have the room for it.

Most places have storage regulations in case of fire, a freezer or fridge would likely satisfy those regs.

I personally don't worry about them and just store powder on a closet shelf keeping large amounts split up in many places.

For long term storage I've put 2 8lb jugs into a thick trash bag, sucked out as much air as possible and twisted it, closed with a bread twisty and placed it in a closet. After 3 years it is still sealed plus it is already in an air-tight container to begin with. Not the least bit worried about it.

Us northerners have basements which stay cooler in the summer months. An air conditioned home works just as well.

I think it's best to avoid temperature and humidity extremes.

My vote would be for a non-working freezer. Strictly for protection from a fire reaching the propellant.
The duct tape idea sounds good. Keeps the lid/door shut and keeps out moisture. The duct tape would blow open IF the propellant were ignited.

My idea was to use a running one. Since cold sucks moisture thought it might help. Or might slow it breaking down.

Maybe ill get a vacuum sealer or something.

I do not really see a need but plenty of freezers use high quality magnetic seals all around the door.

Mine takes a decent pull t open, and the magnets are strong enough to partly compress the rubber gasket.

It takes a decent pull to open since the seal has compressed about 1/4 inch and squeezed a slight amount of air from the interior.
You can hear it escaping for a few minutes after closing the door as you watch the seal compress down in thickness.

It holds about -20 F and is NOT a frost free.
Vacuum packed meat lasts at least a year with no low of quality.

I purchased it when an Uncle was giver a 'depradation permit' allowing over 100 deer to be taken from a corn field near woods.

Ten of us fired from an old concrete chicken coop.

It went surprisingly fast once the deer showed.
They would return after a volley in about 30 minutes and looked rather well fed on his corn crop.

We donated some to a local food bank and each of us ended up with a very full deep freezer.