The Pedant mentions that Polybius describes the second and third steps of the dilectus as assembling explicitly without weapons, then being sent home again to muster again with full equipment. The assumption is that the equipment would be procured or fetched by the soldiers-to-be in the interim.

Sorry, I should have been clearer - since I was addressing the issue of state manufacturing, I was addressing the legions of the Late Republic and Early Empire, not the earlier militia legions.

Scipio does build a “public armaments production center in Carthago Nova in 210, but this may be a one off” (Marian Reforms), and in the view of the Pedant, recruitment of volunteers was an occasional occurrence to sidestep the Senate if they refused to let a commander levy armies the “proper” way but didn’t turn into a regular way to raise troops until the Imperial era.

To my memory, the post-2nd-Punic-War republic by degrees, turned into an effectively volunteer force simply by the low enforcement of the previously-important process of the dilectus - ACOUP even mentions the lack of serious enforcement mechanisms as why eager compliance was necessary, not just passive acquiescence or fear of punishment.

As the wars of the republic became flung further and further afield, issues with recruitment intermittently rose up - not because of poverty or a decreased population, but because some wars in some regions [cough] Hispania [cough] were not popular. People showed up basically as-volunteers throughout the 2nd century BCE, when the shame of not showing up for the little city-state of Rome’s neighboring wars no longer fetches the opprobrium it used to (and even as early as the Second Punic War itself, implicitly not showing up for the dilectus was ’normal’ enough that it was several absences in a time of crisis and near-destruction of the Republic that actually caught notice).

ACOUP also times the dilectus from 290-100 BCE, which is in-line with what I said, and acknowledges a difference between the “Caesarian” legion of the Late Republic and the “Polybian” legion Mid Republic, with his dispute only being how involved Marius was (which is something I acknowledged in my initial comment, “if he was involved at all in changing formal regulations."). Volunteers were the main source of recruits in the Late Republic, with conscription only ad hoc.

His argument that the legions weren’t really a fully professional force until Augustus is arguable, but basically boils down more to the definition of professional than a difference in the facts. ACOUP’s argument is more based around the standing institution of the legions themselves - Augustus’s changes were to maintain the legions as essentially perpetual entities. While in the Late Republic, volunteer professionals who made a life-career out of soldiering very often would end up ‘bouncing’ from legion-to-legion, as legions were raised and disbanded as-needed.

Thus, the legions are not the institutions they would later be, but many of the troops are legitimate careerists. Whether that’s ‘professional’ or not, like I said, is a question of definitions more than anything.