Not knowing any details really and based purely on the information in your post I'd say.. if the target is closer than 45 yards, use the Steyr, beyond that, throw the pellets
Sorry, I couldn't resist
Seriously, the first things I would do would be - proper barrel clean (I'd use a VFG kit), strip the hammer and check for damage. Try running it over a chrono to see if it is perhaps a reg problem. Change pellets.
My money would be on - dirty barrel or batch of pellets that it doesn't like.