before a muzzle loader can be used safely and effectively,  the loading process must be completed in a well regulated manner . . .

Before a rifle can be used effectively, its sight system must be well regulated.   

Sure, it's a mechanical device and everything has to line up 
appropriately .

Cars also have to run before they're allowed to leave the lot  .

Indeed.  A thought exercise for those who have not pondered the wording of the second amendment to our constitution.

Actually I've recently heard a somewhat different take on it that makes just as much if not more sense if you keep in mind what G.Washington, J.Madison, P.Henry both said said about the dangers of a standing army; “Overgrown military establishments, which under any form of government, are inauspicious to liberty, and which are to be regarded as particularly hostile to Republican Liberty." (G.W.) , A standing military force, with an overgrown Executive will not long be safe companions to liberty. The means of defense against foreign danger, have been always the instruments of tyranny at home." (J.M.), “A standing army we shall have, also, to execute the execrable commands of tyranny; and how are you to punish them? Will you order them to be punished? Who shall obey these orders? Will your mace-bearer be a match for a disciplined regiment?”(P.H.),

Sorry for the wall-o-text.
It's clear that the founding father's were aware that a standing military force was a dangerous thing, yet necessary to deter outside aggression.   

I've started to wonder if the "well regulated" statement is in reference to a need for an armed citizenry to keep keep the organized militia (the standing military force) in honest and in check, in modern English something along the lines of, "Finding it necessary to have a small professional military to serve us, we find it equally necessary that the citizenry's right to be armed equally or better than that military be recognized as absolute in order that they may be a deterrent against any attempts by the servants of their nation to become the masters."

Such a reading would put the phrase"well regulated" in line with current usage of the word as well as some of the period usages.   

*Just to throw this in here, a quote from G.W.'s first State of the Union address, "A free people ought not only to be armed, but disciplined; to which end a uniform and well-digested plan is requisite; and their safety and interest require that they should promote such manufactories as tend to render them independent of others for essential, particularly military, supplies."

"Well regulated"  also meant well trained,  and well disciplined.  General Washington had seen enough .... what we today might call "mall ninjas,"  turn up for muster drunk,  with broken or rusty rifles,  or with no powder.   The Militia of the mid 18th century had a poor reputation amongst the British Regulars as well;  they'd tag along to suppress the local Indian uprising but as the hostilities neared,  they'd suddenly remember they had a root canal scheduled that morning .... or forgot to buy wifey an anniversary present ....or any excuse to beat feet.
By the time the Founders came to  debate and ratify the Bill of Rights most knew all too well that the militia system was not nearly as effective as a professional standing army,  and only served well when we'll trained, disciplined and --yes -- equipped.

I don't really get that point of view from what I've read and heard over the years.  The militia was made up of citizen volunteers who agreed to drop everything at a moment's notice and answer the call to take up arms in defense of their respective states or areas.  The standing army was recognized as the main threat from a remote federal government by people who had, within memory, been forced to quarter British troops in their own homes.  The same troops who engaged made war on their countrymen at the behest of a foreign king.  A standing army was anathema to them and the local militia(s) were the counter to it.  A military force made up of local men and led by local officers might at some point join a larger group under a senior commander from another state or area but that would only be under the most dire circumstances.

It is hard to square our modern idea of national defense with the corresponding thought from the 18th century.   The gap is too wide between their reality and ours.  I think the point is an academic one, at best.  We have transitioned to an all volunteer force structure supplemented by a national guard reserve system - which in my opinion, is about as close to the original idea of the militia as we are likely to get under a national defense oriented system. 

Even as early as the War of 1812 it became painfully obvious that the state militias were simply not adequate to the task of repelling foreign invaders.  Despite their success at the Battle of New Orleans, most militias were not up to the task of marching off to war hundreds of miles from their home base.  Several governors of New England states refused to allow their militias to operate beyond state boundaries despite being well organized ( well regulated ) so the need for some sort of standing army was shown to be a priority.  I believe the army stood at something around 7000 men and officers at the outbreak of hostilities - a number clearly inadequate to carry out the task at hand.