Mike C., with the utmost respect for your endless unbounded knowledge, while you are discussing the nomenclature of this "field gun".
I know that what I write here you would already know, and anything I have wrong I am happy for you to correct. I await the barrage.
Here is my personal view:
The term "gun" refers to a smooth bore.
I would suggest in this day and age of political correctness, to stay away from the term "weapon"
I is my belief that the correct usage of "weapon" should be limited to the likes of swords, bayonets etc. (edged weapons) and that small arms or firearms is the term for those sort of things.
I believe that the use of the term "weapons" only hastens the "dis arming" of the good people in this part of the world (my opinion)
Is it not correct that for a rifled artillery "gun" (and I assume the that this gun of topic, is rifled) that David is correct using (artillery) "piece"?