I thought you would have Ball and probably Lapin given the keen interest you have in the particulars of these fine arms.
As you already know, the inspector marks of crown and fraktur character were used almost exclusively by German Empire manufacturers and were not used after the end of WWI. Many other countries did use a crown and letter mark (especially sweden) but the letters were standard letters and not fraktur. This narrows the pool of possible manufacturers of the bolt to probably German Empire between 1898 and 1918.
The most common manufacturers were Prussian or Prussian contract and the Prussian mark is distinctly different than your lion mark. Look at page 169 of Ball 4th edition or at page 105 of Ball 2nd edition.
On the left side of receiver of Danzig examples there's the typical mark found on Prussian parts including the bolt. On the same pages, it's hard to make out, but on the Amberg receiver is a mark that looks similar to your lion and this mark is probably duplicated on the bolt.
The Prussian manufacturers produced a lot of other models besides the Gew98 during this time period but, as far as I know, Amberg only produced Gew98.
dwmmg08 is the one that had the first clue to the manufacturer. I look through these books a dozen times before I find what I'm looking for and still usually miss it anyway. It's too much to know, but the hoppes9 and gun powder sure smell nice