For multiple barrels sets, the forend loops will usually be stamped 1, 2 or 3 for the number of the barrels. And the forend iron will also have the same number stamped on it by the serial number. Providing that there are multiple forends. Which if a gun was ordered with additional barrel sets, they included a separate forend. I have even observed that on a number "2" barrel, even the forend wood had a "2" stamped into it under the iron right next to the serial number.