Personally, I despise the term "negative rights". Recognizing and respecting Natural Rights is not a negative, which is what the progressive left wants you to think.
Anything you must take from someone else to bestow it upon another is not a "right".
For the AR15/AR10 pattern rifles, if you buy a finished barrel with the barrel extension, you won't need headspace gages. If you're worried about it buy a new bolt with the barrel.
"If Men were angels, no government would be necessary. If angels were to govern men, neither external nor internal controls on government would be necessary." - James Madison