You can certainly pump up a Steyr or any other match pistol if you are fit enough! Just get a good quality pump and be carefull to get air filtering to avoid getting moisture in the pistol or cylinder. Divers air which most of us use is safer for the equipment from that point, but I'm sure some one on here with experience of pumping will come along and advise on the protection from moisture which is the only issue other than getting a hernia or heart attack!
Good shooting
Robin
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?