OP, 1-2 of the larger gunsafes on used market can often be an economical way to store ammo. They have better metal thickness than most other containers. Some other tips should you get one.
1. place in corner of room, so walls protect two surfaces.
2. Bolt things down, removal of boxes and safes is a common method for stealing. Also, toppling a safe makes it easier to work above it with a pry bar to flip the door open. Upright it is much harder to deal with.
3. Have door swinging open towards the unprotected side. This is because in order to flip a door while it is standing you need to insert the pry bar and drive it the opposite direction, which will be blocked by the wall on that side.
4. bolt down other room furniture or other objects near the safe, you can even make it a bit of a maze to get them out, felons will have to do a lot more cutting to get them out. This can include bed, beef fridge, cabinets whatever.
5. Hide or lock away any powertools, thieves often will use what is available.
6. Disguise the items, blankets over them, or even large packing boxes whatever. These gunsafes with silly spoke handles and hunting logos over them are too obvious.Unscrew or cut off the spoke handles and just use the knob. Vault handles are only needed for moving door boltwork weighing a ton. They are a sales gimmick on guns safes.
7. Dont tell anyone what you have. People talk, even extended family- one day the wrong ears overhear at work or a bar and you might get a visit one night. Most safes can be beaten pretty easy if a thief has a gun to the owners head.