When a new system is devised and the old terminology is carried over, how can there not be confusion?
I think the point I was making is that the objects themselves are evolving and it is the historic terminology that is being applied to the nearest current equivalent.
I would imagine that a "round" to a musket shooter would still refer to his spherical projectile. Not to me though. I have always understood it to mean either a shot (as in "fire a few rounds down the range") or a complete loaded cartridge, and certainly in shooting terms never thought of a round as referring to a single bullet. My ignorance, but I have never had anything to do with spherical bullets.
The fact that we are using a modified French word for a little ball to describe a pointed cylindrical object does not contribute to sparkling clarity.
We are now using the word describing a thick paper wrapping around a bullet and powder charge "cartridge" to refer to a brass drawing complete with primer, charge and bullet.
I won't bother to answer your analogy to the obtuseness of store men when dealing with the layman. I have been on the receiving end embarrassingly often enough…Four Candles?
Alan
To continue the debate...
Re your para's 1 and 2
They are bullets. It's as simple as that.
There hasn't been a change in over 100 years, roughly.
So where is the "new system" that requires the invention of another name?.
Para 3.
Not being a musket shooter I can't comment on what a "round" means to them.
I understand a "round" to be a military term for a complete unit of ammunition for a small arm (there's another whole thread right there in that term).
Para 4.
Bullet is the name of the item in question
That should give sufficient "sparkling clarity".
Giving it another name merely introduces obfuscation and confusion, such as is happening now.
The etymology of the term could be interesting but that is probably best left to another thread.
Likewise the etymological history of the other items referred to in para 5 which, together, constitute a complete unit of ammunition.
It's a matter of terms, units and standards.
Standards are set by institutions, in the case of our field of interest, firearms, SAAMI, and bullet is a standard term
I can't see any reference by them to "heads", despite the other thread

.
OK, language is a living thing and all that (
Language is a living thing. We can feel it changing. Parts of it become old: they drop... - Gilbert Highet at BrainyQuote) but we are talking technical terms here, it matters more than "a rose by any other name". A rose by another name can get your gun blown up if you see what I mean
The use of language and terms conveys something of the speaker.
As I said before, it can be useful, maybe we should welcome it.
If you look at the names of calibres for pistol and rifle, engineering terms have merged with dates and names to create a world of confusion.
It all adds to the interest though.