George L. essentially has the 25" story correct. However, it was Robert Churchill, not Uncle Ted, that damage his 28" barrels & had them shortened to 25". Robert Churchill was aware of this rumor & always denied it. See page 104 of "The House of Churchill" by Don Masters.
The way I heard the story first, was that Robert was a real promoter & not above embellishing the story. He went off & won the shoot with his shortened 25" gun. When he was asked why 25", he replied, "because my testing has shown that is the correct length!" At least it's a good punch line.
Also from p104, Gun #640 was probably the first recorded gun to have 25" barrels. I own an earlier Churchill 12 ga that appears identical to pictures of the model 25 box lock, but mine has longer barrels and, of course, is not marked with the 25 on the barrels - still a joy to shoot after more than 110 years.
Regards, Ron
