Seen several discussions in archives about similar 20mm x 138 casings as mine shown here. Thought I would share my findings for those who may still be looking for identification.
20/40 = 20 ItK 40 VKT
T = Tikkakoski(Finland)
41 = 1941
Size = 20mm x 138mm
One example found at link below:
http://212.178.67.161/avx/sites/flak2cm/start.php?main_cat=16&sub_cat=130&visitor_level=1&user_id=0&user_name=&session_id=1a58adb6ab8f40bd036103273b25c792&access=view&exp_sub_cat=130
Yes, I have one of those loaded with a dark blue AP projectile but the white stripe is half-way up the projectile, not above the driving band.
My example is E 15 with the same headstamp. White band above the drive band.
