Not familiar, but I have seen those before and there were one or two articles on the ‘net that discussed them.

My memory is vague, but it might actually have been described in an auction.

I worked on one of those a long time ago. To load you rotate the lever c.c. 180* and the block drops down. Can’t remember who made it though. The one I worked on was more of a military configuration.
Tom Klinger

Doing a bit more research it appears to me that LH Hagen was a pretty active gun making concern.
I would also classify this as a Kammerlader and would seem to me to offer good power to help chamber an oversize cartridge.

Here is a link to an LH Hagen converted roller.

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One more, in a rimfire caliber, claimed ot be a conversion, so is the original a percussion gun, like the Norwegian Kammerlader?

and many more in a variety of calibers

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SchwartzStock wrote on Mar 3^rd, 2024 at 11:00am:

Google Translate says it translates to "Piston rifles".  I guess we'll have to wait for someone from Denmark to come along and correct me if that's wrong.

A friend of mine is in the Netherlands and he found a translation to Dutch: (You need to Login or Register to view media files and links)

The word they use is "snellader", google translates that to "fast charger". In German there is what is called "Fach sprache" or professional language for various endeavors. A barrel, like a keg, is Fass in everyday German. A rifle barrel is a "Lauf" but Lauf in the daily language is to run. This is the problem here, google is taking the most common English translation of the Dutch words.