Dear all,
I’d like to represent the cartridge, which may be called as 11x65R forgotten (the epithet is my).

I know that sometimes barrels for 11.15x65R LK were simply marked as “11x65R”, but this is another case. This cartridge is not 11.15x65R LK or 11.15x65 Collath. Also it is not a rimmed version of 10.75x68 Mauser, or 10.75x65R Grundig. The dimensions are similar, but differ and the caliber of barrel differ too. Brass is straight, slightly conical (cone is about 1:100).

It is possible to put rimless 10.75x68 Mauser cartridge in the chamber and it is possible to shot, so even rimless (!) brass arrange good in the chamber, but bullet diameter of mauser’s bullet is smaller than fields diameter of barrel.

Dimensions:
Base diameter 12.55 (0.494)
Rimm diameter 13.85 (0.545)
Neck diameter 11.80 (0.465)

Chambercast:

I have not this cartridge in my collection. But I have a gun! It is old German drilling.
Barrel rifling is very interesting. It is octagonal with narrow fields in the angles of octagon.
Dimentions:
Fields 10.75 (0.423) or a little more.
Groves (sides) 10.82 (0.426)
Angles 11.05 (0.435) or a little less.

The rimm of 38 Special brass is a good choice for slugging my barrel.

The barrel was marked at the beginning as 67/49 gauge (in old German tradition), but later, when the gun was repaired (it has “R under the crown” mark), the calibre marking was re-stamped as 10.7 mm.