It only has a serial under there...?A fair amount is known about barrels. They were either 100% made 'in house', supplied as blanks and finished in house (the most common scenario) or supplied as finished barrels. The entire barrel code is stamped radially around the base. You show dsh and e/623 x2. There is more in between. The e/623 is probably 3 and it was finished by Steyr.