Here's an article that describes some of the red plastic blanks to back a bit of that up... Bakelittfabrikken - General Ammunition Discussion - International Ammunition Association Web Forum
Here's an article that describes some of the red plastic blanks to back a bit of that up... Bakelittfabrikken - General Ammunition Discussion - International Ammunition Association Web Forum
I found a bunch of red plastic blanks yesterday online but none were this large. I had thought I found an exact match off a photo but turned out to be 9mm. I didn't take note of where it was made. 30 carbine rounds that were similar were labeled as Dutch.
Some information I've found this morning states that Norway was where this type of round originated and the patent was held by the company in your link but since then they have been produced elsewhere.
I wiped that one down last night and it cleaned up pretty nice. Had sticker residue on it.
here are some photos of the 20x138mm case, used by Poland and Finland (also Germany
The case is 138mm long
hope this help in your identificationAttachment 111363Attachment 111364