Varieties of originalism
Pejman Yousefzadeh has an excellent discussion of the matter, pointing out that originalism is not a single interpretative tool, but an evolving family of them.
Which one is used dictates what data is to be used. For example: the Journal of the First Senate shows that it voted down a proposal to make the right to arms one "for the common defense." In original intent, this is very important evidence. In original public meaning, it is at most some indication that some people understood an unlimited right to arms, and one "for the common defense" to be different things, and that the first was broader, but that's all. (The Journal of the First Senate wasn't available until years after the ratification; its section on the Second Amendment wasn't widely known until, in the 1980s, I found it in the Interior Department library). The same is true of Madison's notes on the Constitutional Convention, which he did not release until decades later.
Conversely, Tench Cox's newspaper articles on the Bill of Rights, telling readers that the Second Amendment would protect people's rights to keep and bear "their private arms" is vital evidence as to original public meaning, but only moderate evidence of original intent (and that only because Madison's letters to him note that the article was in all the newspapers where the First Congress was sitting).
Then we also have the point made by Eugene Volokh: materials such as these may be valuable, in that if we wish to know how a mechanism operates, and can be made to work well, we would go to the manuals and the designers' notes.