That’s a nice, early-style Swedish dummy in 6.5 x 55! The later ones were all nickeled had only two rings around the case. They are found in with both round nose and spitzer-profile bullets. The latest ones I have seen have the Spitzer bullet proile, with the case nickeled and with two grooves and the bullet anodized bright green, like the 9 mm,. 5.56 and 7.62 x 51 mm dummy rounds from Sweden.
There were smooth case versions of the the green-bullet dummy in 9 mm Para and 5.56, but am not sure about 7.62 x 51 or 6.5 x 55. In 9 mm Para, the variety of dummy types, never mind headstamps since they were made on salvage brass (rejects, etc.) from Sweden is staggering, especially when you consider they have been a neutral country for at least 100 years and have a “citizen” Army, rather than a large professional standing Army.
The 9 mm versions of the dummy rounds can be found in a wide variety of headstamps, including foreign ones, such as the Swedish-contract B DWM B 480C from c.1939 (headstamp NOT exclusive to that contract, of course) as well as Sako and Valtion cases from Finland.