1889 Swiss 4mm Flobert adapter

[Eaglelord17]

This is a photo I found online of the whole kit, it does look like it uses some sort of intermediate for holding the round. (it is the third picture on this page)

International Ammunition Association {iaaforum.org} - View topic - Lienhard 4mm for the Swiss 7.5mm rifle

It appears to just be a drop in kit, my biggest concern is just if there is any chamber modification required, as I wish to use my 1889 with some properly loaded GP 90/23 but am not willing to have my face blown off.

My understanding is this type of kit would be used to practice indoors down the hallway type deal, almost like a airsoft or bb gun with the proper backing.