Just met a guy who has a ME OA visa expiring on the 27 Feb 2023. He has just left and re entered to get a further one year permission to stay. He claims he has been stamped in to the expiry date of the visa, 27 Feb 2023. For example does this mean that if someone has 6 months left on their visa they will only be stamped in to the expiry of the visa not a one year permission of stay?

No idea, but maybe the IO who stamped him in made a mistake?

 

He should go to an Immigration Office and ask and possibly have his stamp corrected.

Assuming he has a Visa that expires on 27th Feb 2023 & not an extension to a visa/re-entry permit that expires 27th Feb 2023 then it seems the Immigration Officer made a mistake. 
 

Best to go to Immigration asap to get it resolved. 
 

Could it be that hi didn't have that insurance they demand that you have for a longer time than the visa. I would guess they won't give the permission to stay without it. But that's just guessing.

He has a valid OA visa that allows unlimited one year entries for a year from the day it is issued.