I know the Finn sling you're referring to and this one ain't it! I have a suspicion this is an IG 71 sling modified to accept a Gew 88/98 swivel adapter. The sling came from a Gew 88 that was parted out. For a while I also thought this might have been a Portuguese Krop. or Vieguero sling due to the wide brass stud but the brass buckle is a Little more "squished" and the leather a little shorter.
Forgive me for saying so Gunluvver but that avatar is one of the most disturbing things I've seen in a while!
The avatar freaked me out when I first saw it. It's one of the selections Gunboards has in the User CP. I saw another version with sunglasses and the flinging hands firing pistols on another board. Looks like she's fed nothing but fast food!