Can Anyone tell Me What This Is?

[Eaglelord17]

In the days when these were being designed and made, the WEAKEST "link" was the ammo.

Note all the attention to designing in "safe" venting of nasty hot gases and brass fragments built into them ALL.

Cartridge failure was NOT an unknown thing, partly because metallurgy was still a relatively new science and "mistakes were made" from time to time. Even as the Mauser 98 was being developed, there was careful consideration given to safely channeling and diverting the nastiness from a failed cartridge case. The Type 38 Arisaka took this to the heights. That is why the striker shroud / safety-catch housings on M-98s and Arisakas are shaped the way they are. Commercially, having "three rings of steel" as your sales pitch, without also having a "plan B" would not be a good thing. Not a lot of risk from factory fodder, but I have seen some spectacular damage caused to modern rifles by hand-loads; either the wrong type / quantity of powder or untrimmed cases playing Hell with bullet retention / pressure curves.

All that attention appeared later on, but many of the earlier designs (earlier Mausers (possibly including the 1893, though I would have to double check), Gewehr 88s, Lebels, etc.) weren't really designed with ammo failure in mind as smokeless was so new, and it wasn't really a problem with black powder rounds. It is interesting what happens in a case failure, I had one with a piece of PPU 7.5x55 brass which I had worked up a GP-90 pressure load for my 1889 Schmidt Rubin. Felt some hot gas come over my face as it is one of those early designs without proper safety considerations, but nothing else negative happened.