At last Ecra’s show, I had the Opportunity to acquire an other 11mm japanese murata cartridges shown below.
While looking a the two cartridges side by side, they have a very different profile. The second one have a copper primer, the case lenght is longer (61,12mm whereas the first one is 59,80mm), the bullet diameter is smaller (10,82mm whereas the first one is 11,29mm) and you could see a small shoulder between the shoulder and the case neck. I wonder if this second shoulder wasmade to adjust the neck to the lower bullet’s diameter. Is somebody had already seen a murata’s cartridge with this profile?