So yes, there will be no more absurdities like cramming an RPG-7 into a toolbox.
First off, Stashes will fall into several categories, essentially 3 main categories, large volume stashes, will consist of things like hatches, large safes, and graves. Medium volume stashes will consist of things like smaller safes, large cases, backpacks, some electrical boxes etc. Small stashes will consist of things like toolboxes, pipes, small electrical boxes, small safes, etc. Different types of containers will contain different types of stashes, some varieties will tend to carry ammunition more than anything else, others rifles, some filled weapon magazines, others will have artifacts, and bare essentials like handguns with food, and medical supplies. There will also be large weapon caches and faction caches, which will essentially be the supply reserves of some of the Zone's STALKER factions.
Hatches, or manholes, are the first type of large stash. Not only do they have a large internal volume, but they are protected from the elements. They are the first logical choice for a faction or a group to store large volumes of weapons and ammunition in one place securely. The downside to this is that they are often visible and prone to being raided. To avoid this, some of these stashes are often found with a large population of mutants guarding them.
Inside this type of stash is usually a small room with concrete walls, and some of them connect to a sewer system. They can easily hold thousands of rounds of ammunition, various weapons, and weapon magazines and explosives.
Faction caches, or rather faction arsenals are usually found inside hatches because they consist of a large internal volume, and are difficult for one person to open. They usually consist of hatches found in areas where a faction has a good degree of control over an area. They are used to store reserves of weapons and supplies in the advent of a war.
Graves are another type of stash. Theoretically speaking, STALKER graves could carry the largest amount of material, because the only consist of something buried under excavated earth, but usually graves contain items such as rifles and artifacts, perhaps some vodka. Sometimes things are left with a dead STALKER as a tribute to his life, other times they are stolen from others, and hastily buried with the dead for someone to pick up later. In any case, graves leave plenty of room to bury things unseen, after all, it doesn't have to be buried directly under the cross.
A large safe is probably the most secure place to put something, so long as it is left locked. These are often used as faction arsenals when a hatch is not around in the immediate area. They usually carry higher-end rifles, rifle magazines, ammunition, suits, and a few artifacts if any. The only reasonable way to open a locked safe in the Zone is to use a cutting torch, and only technicians really have those. Explosives would likely damage the contents inside.
Similar to large safes except they are usually used to contain artifacts and weapon magazines.
Chests, or footlockers are usually used for one thing only, to store ammunition, in vast quantities. They can be locked with a padlock. Occasionally one might find a chest that stores nothing but weapon magazines, either in full or emptied condition. I may add the rare chest here and there that contains nothing but artifacts or dozens of cans of food.
These are the most personal of stashes, because of the fact that they would be actually carried around every day, and thus, they have the widest variety of items in them. Rifle magazines, handguns with their respective magazines, artifacts, and food, and medical supplies, left-over rounds. They're also probably the most common type of stash you would find in the Zone, due to either unlucky saps dying, or just those who threw their heavy sack on top of a truck or something to get away from a monster.
Vary in size, some are large enough to actually contain rifles, others are only big enough to contain a couple pistol or rifle magazines and a medkit or two.
Pretty much only contain artifacts. They aren't really a permanent stash, just a place that someone would put something either immediately after, or before a gunfight.
Artifacts and artifacts only, a handgun with 2 mags would probably be the only exception to this.
Smart article man! really, looking forward to hear more about this :)