Originally Posted by
ludocdoc
What remains unclear to me is what level of security/customs/immigration will exist in between the 2 jetways. In the end, I decided that a 1:25 connection before the transatlantic leg was just too risky either way, so I wont be connecting back through ARN.
It's academic now as you've decided against connecting at ARN... but just for completeness (and for the benefit of anyone else who may be contemplating this):
There will be outbound passport control on leaving Schengen.
In theory there should not be another security check as you will have been screened to EU standards at OSL (these standards apply in all EU and Schengen countries), but not having been to ARN for a few years I can't tell you that for certain because there are other airports (such as AMS) where passengers in transit are re-screened unnecessarily because these airports don't properly separate arriving and departing passengers.
1:25 probably would have been OK (albeit on the tight side), but I quite understand that you wouldn't want to risk it.