Maybe not an app per se, but would it be possible to set up a single page here where you just enter the basics needed to date an SKS, and have it use just the few needed data points to date the SKS in question? A series of drop down menus that narrow down criteria...like an auto parts store website, but kind of in reverse.
You would just have to basically if/then through an inverted flow chart using rules from the dating system to arrive at a date. If it's C&R, maybe include
I have seen similar things on sites for dating guitars from their serials, and they even provide enough info to specify what factory made it. Of course it would be a little more complicated, but sections of the provided data (just the serial) are broken down into months, years and factories.
But it could be available online easily for someone to check via phone. It would also promote the correct dating, if a search could lead to the site even more for 'SKS dating' the better. The old ways still seem to prevail A LOT on other forums and groups...it's tedious.
Mind you, I have absolutely no idea how to write code that would do that, but it seems like it would be something you might even be able to find a template for.