I would bet money 180's in a 9 would be fine even at sea level. I did load development for my nephews 7 mag with a 1-9 Broughton Rbros rifle and its shot great out to 1000.
I'm doing load development on his buds 7 mag as we speak only to 100 so far but I'm getting ready to take it to 500 this is what the last load it shot in upper left with 180 Bergers in a 9
I'm doing load development on his buds 7 mag as we speak only to 100 so far but I'm getting ready to take it to 500 this is what the last load it shot in upper left with 180 Bergers in a 9