Besides the incompatibility with the founding principles, Constitutional rights theory, history and the legal record, any reading of the 2nd Amendment's dependent clause as modifying the independent clause fails as an exercise in English grammar.
The independent clause can stand on its own without the dependent clause and remains true and actionable without any regard to what the dependent clause actually says:
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Being a horrible, violent criminal, Steve shall be put to death at sunset.
Being a wonderful, generous person, Steve shall be put to death at sunset.
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Either way, Steve is taking the dirt nap at sunset.
A dependent clause just can not be read (or interpreted) as creating an iron clad rule or condition:
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All things considered, that is a really bad idea.
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Deciding whether or not an idea is truly bad or not, can not
really depend upon if all things were actually, truthfully and exhaustively considered because that endeavor can never be completed.
Let's try another simple one:
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The teacher being ill, all classes will be canceled today.
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Can classes only be canceled if the teacher is sick?
What if he is really lying about being sick and is actually out playing golf; will classes be held?
Must class always be canceled if the teacher is ill, even for just the sniffles?
Let's see if we can force reading qualifications and conditions onto the independent, restrictive clause in sentences grammatically constructed similar to the 2nd Amendment with an inactive, dependent, declaratory clause preceding the actionable, independent, restrictive clause:
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A well maintained road system being necessary to efficiently commute to and from work, the right of the people to keep and drive automobiles shall not be infringed.
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Can the people only drive on this governmentally maintained road system?
Can the people only use their automobiles to commute to and from work?
Can the people only drive on those specific roads deemed by the government to be necessary for commuting?
Can retired persons or "stay at home" Moms or the unemployed or the independently wealthy be "deautoed" because they do not work?
Can people be prosecuted for taking a scenic route to and from work; is the most efficient route the only one deemed "legal?"
Has a mandate been created that a governmental entity build and always maintain the "well maintained road system" and that system must exist for the people to be "allowed" to drive?
Let's examine another, this one of near identical construction as the 2nd Amendment:
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A well educated electorate being necessary for the perpetuation of a free state, the right of the people to keep and read books shall not be infringed.
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Can people who are not registered and active voters have their right to keep and read books "infringed?"
Can people considered not well educated, including members of the "electorate," have their right to keep and read books infringed?
Are only those books deemed "necessary to the perpetuation of a free state" to be owned and read?
Can access to particular books deemed to not directly be "necessary to the perpetuation of a free state" or deemed to not directly promote a, "well educated electorate" be restricted with permits / licenses / tax stamps?
Does the right of the people to keep and read books only exist for them to be well educated voters and to perpetuate the free state? Can all other creation, aquisition and uses of books be restricted, qualified and conditioned and books themselves that do not meet that criteria, be banned by government?
Hopefully you answered no to all those questions.
If you did then I must ask . . .
Why do you read such nonsense into the 2nd Amendment?