Damn you beat me to it :rotf: But I prefer to believe the one in question doesn’t want to post pictures period .

Direct link to the article
https://archive.org/details/sim_amer...ge/20/mode/2up

Scroll down about 1/3 here for more information, including a 1897 study & Charles Askins quoting W.A. King.
The issue seems to have been "overlap"
https://docs.google.com/document/d/1...vwLYc-kGA/edit

(All you have to do is L click your mouse thingie on the link Bill :rolleyes: )

Try this for easier reading, maybe.

I still think it is a question of chicken and egg. Following the thought process here, chambers were 2-1/2"; ammo makers lengthened shells for more performance to 2-3/4"; someone ran some cursory tests with pretty little data collected and pronounced the that long shells in a shorter chamber gave better performance; gunmakers after bragging rights decided to shorten the chambers to take advantage of that performance; ammo makers shortened their new shells to stay safe.

That's a lot of changes with little real data and even less factual proof that is what happened.

What is true is that in a later era with the proven performance of one piece cup wads, performance was elevated to an entirely different level and then improved again by modern design of barrels with long forcing cones and overbored barrels (which shouldn't even work based on the original theory). Trap shooters led the way and today no one builds a high performance shotgun without those features. The same features worked just as well before the plastic cup wads. Look at the work done by Becker and others and the legendery performance of the NNID Ithaca 10's and the Super Fox. The Parker was ahead of the times and normally used overbored barrels in their 10 and 12 guns, many of which performed very well with cylinder bored barrels.

The fact is that a long forcing cone with it's very shallow taper gives a smoother transition and the overbored barrel drastically reduces the effect of scrubbing on the shot column.

The proposition might make for an interesting history discussion (although proven details are nebulous) but they are neither here nor there as far as modern performance is concerned. Shoot appropriate shells the same or lesser length than the chamber and loaded with modern components, and everything will work well.

Not everyone is convinced that bore size or forcing cone length matters; including Neil Winston
https://www.trapshooters.com/threads....365553/page-4

Neil Winston “Have Today's Increased Bore Sizes Improved Trap Gun Performance?” 2016
https://web.archive.org/web/20180829...e_Diameter.pdf

And for a historical perspective, the chamberless Tolley "Altro" was introduced in the mid-1890s
https://books.google.com/books?id=BF...AJ&pg=PA31&lpg
https://books.google.com/books?id=Bz...AJ&pg=PT92&lpg

Dr. Charles J. Heath chamberless patent
Forest & Stream July 1921
https://books.google.com/books?id=x1...J&pg=PA308&lpg

1922
Sporting Firearms of Today in Use
https://books.google.com/books?id=9X...AJ&pg=PA95&lpg

Field & Stream, August 1922
https://books.google.com/books?id=XQ...J&pg=PA470&lpg

A few Lefever have been documented with "Taper System of Boring"; gradual constriction from end of chamber to the muzzle.
Forest & Stream 1909 "First to adopt the taper choke system."
https://books.google.com/books?id=l0...J&pg=PA395&lpg

Charles Askins on "taper choke" in October 1917 "Recreation"
https://books.google.com/books?id=gX...=RA1-PA210&lpg

https://photos.smugmug.com/US-Makers...20Stream-L.png

Daryl Hallquist has confirmed that an occasional Lefever 12 gauge has bores tapering from the breech to the muzzle (.756 to .708 left and .715 right on one gun). Most have a standard U.S. .729 - .732" parallel bore.

Actual performance testing as opposed to marketing hyperbole

Jim Eyster 2010
http://www.jimeyster.com/testing/doc...one%20Test.pdf

Matt (discusses increased volume post-cone lengthening)
https://www.trapshooters.com/threads.../#post-8585555

Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the “Field” Newspaper, Relative to Firearms and Explosives, Volumes 1-2, 1897, “The Junction of the Chamber and the Bore”
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA303