"ALL" guns should have their bores & chambers examined prior to ever placing a shell in the chamber & the older it is the more important this is. With all due respect to Mr Fergus (I have read his account of this also) to have ever fired that first shell in which the mouth of the case would actually open into the "Bore" itself was nothing short of Utter Foolishness. That stepped or Extremely short angled cone should have been well noted & "NO" shell fired in that gun of which its fired length exceeded the chamber length.
Miller, the problem with the above is that we, right here, often lead folks astray on the above practice. Someone has a short-chambered gun; what's the response? "Well, if you want to be safe and don't reload, just shoot 2 1/2" shells in it." Only problem there is, some shells marked 2 1/2" are longer than that. Right on the box of Kent Gamebore Pure Gold shells I have, it tells me that shells with a "65/67MM case length" are suitable in "Guns with a chamber length of 2 1/2" or longer." So, mine's got 2 1/2" chambers . . . they ought to be safe regardless of what's beyond the chamber, because the shells are British, my gun's British, and it fits the description. (Maybe we should always add a caveat when we tell them all 2 1/2" shells are fine.) But they're not--as demonstrated by what happened to Fergus--if their fired length happens to exceed 2 1/2" (which it might). I suppose Gamebore's "out" there is the rest of the sentence, which reads: "Nitro proofed to a service pressure of 3 tons per square inch (850kg per square cm)." Those proofmarks, of course, are only found on guns made (or reproofed) since 1954--which would eliminate the pre-1900 guns, unless they've passed modern reproof.
