You have to wonder why they make it so confusing. A loaded 2 3/4" shell is actually 2 1/4" long -- if it's a folded crimp, after it's fired it measures just under 2 5/8"

So why are they called 2 3/4" shells?

What average joe hunter would think it's ok to fire 2 3/4" shells in a gun with a 2 5/8" chamber?

If the gun with 2 5/8" chambers had the chamber length marked on the barrel would it say 2 5/8" or 2 3/4"?

The first picture from left to right:

loaded 2 3/4" 28 ga, fired 2 3/4" 28 ga, loaded 2 3/4" 20 ga, loaded 3" 12 ga, loaded 2 3/4" 12 ga, fired 2 3/4" 12 gauge

Second picture:

fired 2 3/4" 20 ga measures 2.618" (just under 2 5/8")

Ron, not all shells of the same gauge are exactly the same length when fired.

“Average Joe hunter” needs to familiarize himself with chamber length and barrel wall thickness and the type of ammo he thinks he can use in these classic old doubles. If that’s too much trouble for him, he really has no business shooting classic old doubles.

A 2 5/8” chamber was made to shoot 2 3/4” shells. The shell when fired, would open about 1/8” into the forcing cone. The belief was that this would provide a better gas seal.

I also have 20 gauge Parkers with 2 3/8” chambers that were made to shoot 2 1/2” shells.

There is also a ‘stretch’ factor in plastic shells and none of the modern plastic shells were manufactured with the requirements of our classic old doubles.



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Apparently, the SAAMI meeting where it was "suggested" that our manufacturers begin marking the chamber length on their shotguns was in 1937, and we begin seeing such markings on 1938 or 39 guns. Some examples from Remington autoloaders, August 1935 --

Attachment 74398

May 1937 --

Attachment 74400

April 1943 --

Attachment 74399

What Dave said.
A.P. Curtis published an article in the March 1938 American Rifleman entitled “Advantages of Short Shotgun Chambers” (courtesy of Larry Brown):
SAAMI, assembled in serious conference on March 26, 1937, passed the following resolution: “That an appropriate warning label be placed on all boxes containing smokeless powder shells, cautioning the consumer against using them in short chambered guns and also in guns with Damascus barrels and guns not in first-class condition.” The motion was made and seconded by representatives of two powder companies.
That same conference also passed a resolution requiring: “That all guns be marked so that the consumer will be able to tell the chamber length, as for example by marking 2 3/4 inch chamber etc.”

Hunter Arms lengthened the 20 gauge chambers from 2 1/2" to 2 3/4" in 1936.

Dean -- if a 2 3/4" shell actually measures 2 1/4" (see my picture in post above) and when fired measure less than 2 5/8" (see second photo) how does it "open about 1/8" into the forcing cone?"

By my measurements the fired case doesn't even reach the forcing cone. So there is no way they could create a better gas seal. Maybe loaded roll crimp cartridges are longer than loaded folded crimp cartridges? I don't have any to measure.

Ron, you're missing one basic fact... These guns were built to the specifications of paper shotshell casings manufactured (cut) to specific lengths. All of the ammunition manufacturers (and there were far, far fewer then than there are today) adhered to specific measurements for paper shotshells.

We can't compare apples to oranges as in shotshells manufactured in the latter half of the 19th century and early 20th century and those manufactured today.

By the way, and please correct me if I'm wrong, the only shells in your picture of six that appear to be factory new are the two in the center.... the other four appear to be reloads.





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Here is something that has been posted before. Scroll to about page 15 or so. The rest of the reading is pretty cool, too!

https://docs.google.com/document/d/1...vwLYc-kGA/edit

I don't believe I'm missing the point -- I made that very point in my last sentence about roll crimped cartridges. I totally understand the difference between modern manufactured plastic hulls and the older paper shells.

Regardless of the material used, the cartridge has one length when loaded (roll crimp or folded) and a longer length after it has been fired. Although I read about the 1/8" into the forcing cone theory in the article Scott Chapman provided a link to interesting it doesn't make sense to me. The paper hull obviously has a certain thickness and if it is not allowed to open fully (because it is 1/8" into the forcing cone) the wad and shot column would get squeezed down to a smaller diameter before entering the bore. How can that possibly be a good thing? To me the ideal would be for the cartridge to open fully in the chamber allowing the wad and shot to enter the bore without any constriction. Obviously the chamber length can't be so long that gas can escape around the wad. The other factor is the chamber diameter and hull thickness -- I would think the prefect situation would be to have the inside diameter of the hull (after being expanded by the gas pressure) be the same as the bore diameter -- that way the wad and shot column could make a smooth transition from the hull into the bore -- a difficult task since hulls don't all have the same wall thickness.

Check out this illustration, esp (c) showing the expanding gasses escaping past the squeezed down wad and shot column (caused by the hull opening into the forcing cone):

Here is the source of the attachment above:

https://books.google.com/books?id=in...page&q&f=false

May we know the author of this work of compilation?
We see the names of a few of our PGCA friends so can we presume this was compiled by Dr. Drew Hause?





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