Identify German 10.75x54 mm cartridge

[Karl]

I'd like help to identify this rifle cartridge. -- 10.75x54 mm rimmed -- for a J.P. Sauer hammer drilling built in 1891. I took a chamber cast with Cerrosafe. The dimensions of the cartridge are:
54 mm (2.11") length
12 mm (.472") base
12 mm (.472") neck
13.4 mm (.528") rim diameter

Thanks for any info or leads.

. Drilliing Rifle Cartridge cast.jpg

[mike ford]

Herman,
See my comments above, in your thread about identification of the drilling. 11.15x52R LK Express (of course I might be wrong).
Mike

[Karl]

Mike just saw your post. Here's what I've discovered:

Using pin gauges I determined that the bore is .424” (10.76 mm). With light taps I easily drove a .428 lead bullet though the bore filling the Henry rifling. Allowing for a short free-bore throat the closest match I’ve found so far is the 10.75x52R Grundig cartridge. However, the Grundig dimensions and chamber cast dimensions do not match exactly. Identifying the European cartridge may not be necessary as I have found that a dummy .410 shell fits perfectly, including the rim fitting the extractor, except it is too long and engages the rifling. I’ve ordered .410 2 ?” brass cartridges and will cut the cases to 52mm. I’ll assemble a couple of test cartridges.
I'll update you after I test a round.