Unknown cartridge

Based on 6.5×50SR,bullet diameter 6.48mm,case length 51.94mm

A few more dimensions please.
Bullet diameters outside neck are always smaller than correct bullet diameter, so unreliable as an ID feature.
Pointed cartridge is T38 (1905) design 6.5x50SR for the Japanese
T38 rifle whilst
Cylindrical Round nose cartridge is
6,5x50SR T30 ( 1897) cartridge for the Type 30 Arisaka Rifle.

Ammunition of both types was supplied to Tsarist Russia by Japan via Britain, and British companies made the .256 Mark I
(T38) and .256 Mark II (T30). ( Kynock, etc). They got the dates
Un-head-stamped cartridges will be Japanese make, Kynock cases are headstamped K with date.

Doc AV

I got the diameter after I pulled the bullet off.
And I will make a detail measurement later

Early 6.5mm UK rounds were also unheadstamped.

Both Kings Norton & Royal Laboratories produced this calibre with no headstamp.