In addition to what Topgun has noted, the records will also indicate if the gun was shipped as a two barrel set. The length of both barrels will be given. Occasionally, a later additional barrel set will also be listed.I have two, two barrel sets. One is a 2E that was ordered with two barrels in 1906 and the ledger entry shows both barrel lengths. The other is a PE grade shipped in 1909 with chain Damascus barrels. In 1927 that gun was sent back for a set of steel barrels and the additional barrels were entered above the original entry.