The speaker, evidently a new recruit to the British army, is standing at attention with other soldiers while receiving instructions about the rifles they are holding, therefore the naming of parts is associated with the pieces of the guns in front of them. The speaker obviously hates being formed into a soldier by such an impersonal, assembly-line process. He does not want to be a soldier. He is a sensitive person--a poet, in fact--and he can't help noticing and responding to the beauty around him while listening to the lecture on how to disassemble and reassemble his rifle.
In the first stanza he says, or thinks:
We had daily cleaning. And to-morrow morning,
We shall have what to do after firing.
It seems the drilling and instruction are endless. He has no freedom, no choice. He is part of something as mechanical as the rifle he has been issued. He must stand like a robot until dismissed and must come back tomorrow for more of the same. His thoughts and feelings are similar to those of millions of young civilians who were sucked into the military machinery all over the world, including, no doubt, the enemies in Germany, Italy, and Japan. He doesn't hate anyone. He doesn't want to have to kill anyone. But he has no choice in the matter. World War II is underway. All eligible men are being called up. Some of them, like the speaker, are not good soldier material, but they are being molded into soldiers just the same.
As each part of the standard service rifle is explained, this hypersensitive speaker sees in it a simile or metaphor for something beautiful in nature which is the antithesis of war and killing. Naturally, he would like to be free of his uniform and his rifle, the barracks and the mess hall, and to be able to indulge in appreciation of freedom and nature, but he keeps beimg reminded of his situation and of his future by the interminable naming of parts.
Glistens like coral in all of the neighoring gardens,
And to-day we have naming of parts.
The stanzas alternate between what the speaker is hearing and what he is thinking and feeling. He is not feeling mutinous. He does not dispute the necessity of mobilizing for the war against such dangerouos enemies as Germany and Japan, both of whom are on the offensive at that time and threatening to conquer much of the world. "Naming of Parts" was published in 1946 but must have been written much earlier. The war started in 1939 for Great Britain and ended in final Allied victory for the 1945. It was in every respect the greatest war in the history of the world, and it was an experience of tremendous importance for those who survived.
According to the Magill's Cyclopedia of World Authors, Fourth Revised Edition (accessible via eNotes; see reference link below):
In 1941 he was drafted into the Royal Army Ordinance Corps. His skills with languages, especially with Italian, soon earned him a transfer to the Foreign Office’s Government Code and Cypher School, and for the remainder of World War II he served as a translator for naval intelligence.
After the war, Reed pursued a career in writing and specialized in scripting radio dramas.
Reed quickly established himself as one of the best and most reliable of the large stable of writers creating dramas for the BBC, and his popular acclaim for these works lasted in England beyond his lifetime.
In spite of his success as a writer, Reed did not have a happy life. He was a gay man in a society that made life for gay men difficult, and he had only one sustained romantic relationship during his lifetime.