First of all; "Disciplining" also carries with it a sense of authority and oversight, which is practically the definition of "regulation" as we use it today, although we tend to see it as an executive branch function and the founders saw it as a legislative responsibility. And the real thrust of "disciplining" the militia as provided for in Article 1, Section 8 was intended to provide "uniformity" among the various militia units as
Federalist #29 makes clear.
Hamilton, generally considered to be the sole author of Federalist #29, is the only one of the founders we have -- unless you have another to offer -- who gives us his take on "regulation" and the militia and he makes very clear that "regulation" does refer to both "direction" and "discipline" as quoted here in Federalist #29, paragraph 2:
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. . . This desirable uniformity can only be accomplished by confiding the regulation of the militia to the direction of the national authority. It is, therefore, with the most evident propriety, that the plan of the convention proposes to empower the Union "to provide for organizing, arming, and disciplining the militia . . ."
Hitting the highlights, uniformity is accomplished by regulation under the national authority, therefore the plan for discipling the militia . . ., etc. Regulation is a concept of the delineation of authority, something which suggests the "properly functioning" concept you propose falls short in my opinion.
There is more in Federalist #29 that makes clear that the intention of the founders was that Congress was undertaking a duty to exercise its authority as the "guardian of national security" in regulating the militia.
From paragraph 3:
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. . . If a well-regulated militia be the most natural defense of a free country, it ought certainly to be under the regulation and at the disposal of that body which is constituted the guardian of the national security . . . ."
The phrase "under the regulation" is directly at odds with any argument that the founders intended "regulation" to mean solely an "efficient" or "properly functioning" type of relationship. Use of the word "under" alone refers to a relationship of authority.
The notion of "regulation" as implying authority is strengthened even further, later in Federalist #29 when Hamilton associates "regulation" with the word "command" and is further extended to envision the federal government "prescribing regulations" -- which can only mean "regulate" in the sense of authoritative management -- as stated in paragraph 9:
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. . . What reasonable cause of apprehension can be inferred from a power in the Union to prescribe regulations for the militia, and to command its services when necessary, . . ."
Against all of this clearly-stated intent cited from the
Federalist Papers I would have to ask for an accompanying counter from another authoritative source of the period speaking to the meaning of the militia clauses of the constitution to hold it up against and which suggests that there is no intent to regulate the militia other than to suggest maintaining its proper functioning. The stated goal in Federalist #29 was clearly a relationship of authority.
And El Gato, I do hope you caught the rest of my post #233 in which I made clear that the 2nd Amendment use of the term "well regulated" only recognizes that Congress has the power to regulate the militia as a collective body and that this does not extend to any power to regulate individual gun ownership.
Again I state that "well regulated" was and and is a "term of art" that meant and means more than regulated well. Hamiliton speaks of regulation when he is speaking of the exercise of the powers Congress has over the organization and discipline which flows from Congress to the Militia. When he talks of the character he wishes the militia to have, he uses "well regulated". In this sentence, extracted from your link, he uses both terms, as I have explained above:
If a well-regulated militia be the most natural defense of a free country, it ought certainly to be under the regulation and at the disposal of that body which is constituted the guardian of the national security. If standing armies are dangerous to liberty, an efficacious power over the militia, in the body to whose care the protection of the State is committed, ought, as far as possible, to take away the inducement and the pretext to such unfriendly institutions. If the federal government can command the aid of the militia in those emergencies which call for the military arm in support of the civil magistrate, it can the better dispense with the employment of a different kind of force. If it cannot avail itself of the former, it will be obliged to recur to the latter. To render an army unnecessary, will be a more certain method of preventing its existence than a thousand prohibitions upon paper.
"Well-regulated" is an adverb describing the desired character of the militia. "regulation" is in this case a noun, but one that indicate the action of the verb "to regulate".
Also federalist 29, and the others, are discussing the provisions of the Constitution as proposed, before the Bill of Rights were written and passed. If there is a conflict, which there is not, IMHO, then the amendment would control, as that is the nature of the action of an amendment upon the document amended.