How do I individually load a bullet into a gun?

If I don't have a magazine/clip to a gun in DayZ, how do I load a single bullet into the chamber if I have the proper ammo for it?

Say I have a 9mm handgun and 9mm bullets, how would I put a 9mm bullet into the chamber of the 9mm handgun?

There seems to be a bit of confusion among various forums about this, but one forum that I found states:

You can chamber 1 Round into the gun without a Magazine otherwise for more than 1 bullet you need a mag

Also In order to put a bullet into a gun it has to be out of the box like the 7.62 you find in boxes empty them and it will turn into a stack of 20 said bullets then you can chamber em

If the ammo is in a box, try emptying them out first, then try dragging the ammo up into the weapon in your inventory to chamber it.

This video demonstrates with the Mosin how you can load just a single bullet. Open your inventory, select the ammo, and drag it up to your weapon. A drop down should appear that allows you to either "Load Ammo" or "Chamber [weapon name]". Selecting the "Chamber" option will load a single bullet.

Other sources I've found make it seem like you have to have a magazine for some weapons in order to load ammo into it at all. In the case of a Mosin, there is no need for a magazine, allowing you to chamber it. You can try doing this for you pistol, but if it does not work, then I assume it needs a magazine to even be used.

Tab out and drag the ammunition from your inventory onto the gun - the ammo should highlight orange to signify that it is compatible, it will chamber the round on mouse up.

Or

Hotbar the weapon and the ammo round/stack, whilst the weapon is in your hand hold the key for the hot-barred ammunition, it will chamber it the round. - This is the preferred method for when you are in a PVP situation without a mag as you will not need to tab out.