A cartridge consists of case, fitted with a primer in the base, powder inside and a bullet in the front.
It is incorrect to say that a firearm is loaded with bullets.  A firearm is loaded with cartridges. Bullets are loaded into cases, forming the cartridges.
Sometimes other words are used when describing a bullet.  Incorrect words are 'head', 'point' and 'projectile'.
'Head' and 'point' are used as in 'bullet point' or 'bullet head'.  The implication is that 'head' and 'point' are the parts that are fired from the firearm and that the 'bullet' is the part that is loaded into the magazine. This is incorrect as bullets are loaded into cases to form cartridges and cartridges are loaded into a magazine or chamber of a firearm. 
That is why the uninformed has difficulty with the terminology and where the incorrect use of 'loading the gun with bullets' comes from.
It is also why Officials who make regulations that govern flying, posession and transport, do not understand that bullets and unprimed cases are harmless.  They think incorrectly that 'bullets' are cartridges or ammunition and act accordingly.  We, as knowledgable people should use and teach them the right terminology.
A projectile can be a bullet but it is a collective term.  'Projectile' is any object that is launched and could be a cannonball, piano (if you have a trebuchet that is big enough), pumpkin or a bullet.
The words cartridge, casing, primer, powder and bullet can denote only one thing when speaking in the context of firearms and there is no confusion when using these words.
The simplest way of remembering the terminology is to start with the bullet.  We say, correctly, that a person is wearing a bullet proof vest or that there are bullet holes in a target. We do not talk about 'head' holes or 'point' holes in a target and a firearm is not chambered for a 'bullet'.  A firearm is chambered to accept a particular cartridge.
Use the right words and be understood, reduce confusion and be correct.

The parts of a primer

The Parts of a Casing

The Parts of a Rifle



GS Custom Bullets, situated in Port Elizabeth on the East Coast of South Africa, manufactures solid copper, turned, monolithic bullets for hunting and sport shooting. These bullets are used by hunters on several continents, hunting from the smallest of antelope to the largest of dangerous game, using the smooth HP bullet, as well as the more popular HV, FN and SP bullets with the patented drive band concept. GSC bullets are configured for the highest possible ballistic coefficients. SP bullets are mainly used for sport shooting. All GS Custom Bullets are coated.