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*Last edited by revdocdrew on Thu Sep 14, 2006 4:10 pm; edited 2 times in total*

This topic comes up so frequently that I thought I'd post this from the Fox Collectors Forum written by Researcher (who knows his stuff) This was published in The Double Gun Journal, Volume Fifteen, Issue 4

FOX CHAMBERS --

The only two A.H. Fox Gun Co. catalogues, that I have seen, that state chamber lengths are the 1913 and 1914. They both state 12-gauge guns are regularly chambered for 2 3/4 - inch shells, 16-gauge 2 9/16 – inch shells and 20-gauge 2 1/2 - inch shells. That being said, virtually every 12-gauge Ansley H. Fox gun made in Philadelphia (other than the HE-Grade Super-Fox) that I've run a chamber gauge in shows about 2 5/8 - inch. The chambers of unmolested 16-gauge guns seem to run about 2 7/16 inch and 20-gauge guns a hair over 2 3/8 inch. A very few graded guns were ordered with longer chambers. I have a 1920-vintage AE-Grade 20-gauge that letters as being chambered for 2 3/4 inch shells. Its chambers are 2 5/8 inches. Savage began stating chambered for 2 ¾ inch shells in their 1938 Fox catalogues.

All this being said there is a good body of evidence that back in those days chambers were held about 1/8 inch shorter than the shells for which they were intended. In the recently published book "The Parker Story" the Remington vintage specification sheets on pages 164 to 169 call for a chamber 1/8-inch shorter than the shell for which it is intended. Also in the 1930's there were a couple of articles in "The American Rifleman" (July 1936 and March 1938) on the virtue of short chambers. A recent issue of The Double Gun Journal carried an article on tests showing no significant increase in pressure from shooting shells in slightly short chambers. IMHO I don't much sweat that 1/8-inch in 12-gauge guns. On the other hand when one gets a 20-gauge chambered at 2 3/8-inch likely intended for 2 1/2-inch shells I do worry about folks firing 2 3/4-inch shells in such guns.

Also, Askins mentions (Modern Shotguns and Loads, 1929) that for the last 3 years or so the US makers started to hold their chambers shorter since the constriction made when shooting 2-3/4" loads in 2-5/8" chambers was found to improve patterning.

My only (possibly intelligent) contribution is that pressure and recoil are not necessarily the same thing. It would seem wise to avoid any increase in recoil when shooting a classic SxS that may have 100 year old wood. I can certainly testify that recoil is brutal shooting AA 2 3/4" 7/8 oz. target loads in my 2 1/2" chambered 20g 1922 Trojan (which actually measures closer to 2 and 3/8".)

Member Joined: 26 Apr 2005 Posts: 743

Drew, that's a good point--and I'd guess that the worst problem with 2 3/4" in short chambers would be with 20's, because they had the shortest standard chambers of all, at 2 1/2". If you had a gun with very short cones, the case mouth might almost make it into the bore. The recoil with your Trojan might be worse because of a short and possibly low stock. That's often an additional issue with old 20's. I shoot factory 20's all the time in an Arrieta that's certainly lighter than your Trojan, but of course it has modern chambers and modern stock dimensions.

L.C. Smith changed the 20 ga. from 2 1/2" to 2 3/4" in 1936, my L.C.Smith 16 ga. circa 1939 has 2 9/16" chambers. A 1938 Fulton was still 2 9/16".

ITHACA CHAMBERS -- The last Flues period catalogue (1925) states -- "Unless otherwise ordered Ithaca 28 Gauge and 20 Gauge guns are chambered for the standard 2 1/2 inch shell, 16 Gauge and 12 Gauge for the standard 2 3/4 inch shell and 10 Gauge for the standard 2 7/8 inch shell. Longer chambers are furnished if ordered on new guns without extra charge, but it should be remembered that shells of standard length do not give quite as good results in chambers which are longer than the shells and it should be remembered that extra long shells are more expensive and it is much harder to find a dealer who carries extra long shells in stock." I find that 2 3/4 inch pretty strange in the 16-gauge, because 2 9/16 was the standard 16-gauge shell until WW-II!?! None of my earlier Flues period catalogues mention chamber lengths.

Beginning with the first NID catalogue in 1926 they state -- "Unless otherwise ordered Ithaca .410 Cal. and 20 Gauge guns are chambered for the standard 2 1/2 inch shell, 16 Gauge for 2 9/16 inch, 12 Gauge for 2 3/4 inch and 10 Gauge for the standard 2 7/8 inch shell." The 28 gauge doesn't appear in NID period catalogues until 1932 though they did make some. Beginning with the 1927 catalogue the sentence is changed to -- "Unless otherwise ordered Ithaca .410 Cal. guns are chambered for the standard 2 1/2 inch shell, 16 Gauge for 2 9/16 inch, 20 and 12 Gauge for 2 3/4 inch and 10 Gauge for the standard 2 7/8 inch shell." Ithaca catalogues for 1926, 1927, 1927-1928, 1928, 1928-1929, 1929, 1930, 1931-1932, 1932, No. 50F, and No. 51S, all list 16-gauge as 2 9/16-inch chambers. Beginning with the 1932 catalogue the 28-gauge with 2 7/8 inch chamber is added to the list and it also introduces the 3 1/2 inch Magnum Ten Gauge. By Ithaca catalogue No. 51F the 16-gauge is finally listed with 2 3/4-inch chambers and the 410-bore with 3-inch chambers. I believe the catalogues No. 51 equate to 1934.

*Last edited by revdocdrew on Fri Sep 15, 2006 4:58 pm; edited 2 times in total*

From the Parker Gun Collectors Forum:
http://www.parkergun.org/forums/forum1/2164.html

Parker "borrowed" English chamber measurements (for paper shells) and manufactured 12ga and 16 ga 2 1/2" chambers until about 1895...then the 12 ga went to and continued with 2 5/8"chambers (16ga went mostly to 2 9/16" ) for a long period...possibly until near the end of regular Parker production...about 1934. By 1930 most (but not all) shotshell and gun manufacturers agreed to 2 3/4" chambers for field and target guns. As far as I can determine, 2 5/8" shells were manufactured at least until 1940. The 1945 Stoegers Shooters Bible lists Xpert and Xpert Super Skeet loads, Ranger Field loads, and Leader Staynless loads as being available in 2 5/8" 1 1/8oz. By that time all Super-X, Super Speed, Leader Super Speed, Ranger Brush Loads, etc were 2 3/4" 1 1/4oz. Original chamber length is a strong clue as to the correct MAXIMUM shot load.

I don't know what to make of the 1920 "2 1/2" Standard Shotgun Chambers drawing" (p519 TPS). Some information is obviously missing. In original 12ga chambered guns (frame size #2 and smaller), a 12ga .798 chamber gauge will stop most commonly at either 2 5/8" or 2 3/4". Why does a .798 gauge not stop at 2 1/2" as depicted in the drawing? The difference due to chamber taper is of course, negligible, but why would Parker make a "shop drawing" and not use it? Why was this 2 1/2 inch "standard" adopted in 1920 when Trap Guns were standardized at 2 3/4 inch chambers much earlier? Is there documented evidence to validate the "better gas seal" claim? Is there "short chamber" patent?

In the recently published book "The Parker Story" the Remington vintage specification sheets on pages 164 to 169 call for a chamber 1/8-inch shorter than the shell for which it is intended. I have a 1930-vintage VH-grade 0-frame 20-gauge and its chambers are 2 3/8 inches intended for the old 2 1/2 inch shells, eight years after the 20-gauge Super-X shell was introduced in a 2 3/4 inch case!!

New subject: Why would manufacturers continue to make 2 5/8" shells 15 years after they had adopted a 2 3/4" standard?

Presumably because 2 5/8" shells were designed to work in 2 5/8" chambers with a maximum 1 1/8oz shot load AND those shells worked equally well in 2 3/4" chambers. If there was gas leakage around the overpowder wad or in the forcing cone, no one was the wiser...or complained apparently. We shoot 2 3/4" shells in 3" chambers today (ex Ruger Gold Label) and no one raises an eyebrow. Conversely, 2 3/4" 1 1/4oz loads were NOT DESIGNED to work in light guns with 2 5/8" Chambers.

Things are different now. No one makes 2 5/8" chambers anymore and we have shot loads at 1 1/8oz (and less) for 2 3/4" shells.

The 1923 Remington catalog has many 12ga shell listings and about 90% are 2 5/8". Even the Nitro Club Trap shells were 2 5/8 inch 1 1/8oz at a time when Trap guns had 2 3/4"chambers. Apparently there was no disadvantage.

If you read the DGJ articles, you will see that the difference between a shell made for 2 3/4" chambers, when shot in a 2 5/8" chambered gun versus a 2 3/4" chambered gun is approximately 300psi out of a total load psi of 7000-10,000psi.

Member Joined: 26 Apr 2005 Posts: 743

The main reason that manufacturers continued to make short shells (2 5/8" 12's, 2 9/16" 16's, and 2 1/2" 20's) after they switched to a 2 3/4" standard is quite simple: There were still a lot of short-chambered guns out there. And while shell length does not increase pressure significantly in and of itself, the 2 3/4" factory shells were loaded to higher pressure standards than their short predecessors. This was not a huge increase, according to sources from the period--about 1,000 psi. But the new, longer shells definitely were higher pressure than the older, short ones.

I have the two American Rifleman articles to which Researcher refers above. And here's the reason why better patterns resulted from slightly overlength shells in short chambers (or chambers marked 2 3/4" that weren't really that long): Remember that we're talking the pre-WWII days, paper cases and felt or cork wads, no plastic shotcups. One reason for pellet deformation back in those days is that the unprotected pellets would slam into the walls of the forcing cone when the gun was fired. However, if the paper case mouth opened into the forcing cone, the mouth of the shell itself afforded some protection to the shot charge, on its initial contact with the bore. Tests established that slightly shorter chambers resulted in tighter patterns. Some trap shooters even when so far as to shoot 3" shells in 2 3/4" guns. Today, of course, with plastic hulls and wads, there's no longer any pattern benefit to shooting longer shells in short chambers, because the wad itself does a much better job of protecting the shot.

*Last edited by revdocdrew on Sun Oct 15, 2006 4:43 pm; edited 1 time in total*

From another forum:

The Winter 2001 Double Gun Journal has the article by Sherman Bell called "Finding Out for Myself" Part V "Long Shells in Short Chambers".

After extensive testing carried out in a very professional manner he concludes:

"With loads that are sensible in a light 21/2 inch gun, we see no dangerous pressure levels produced. I see no reason, related to safety, to modify an original 2 1/2 inch chambered gun to shoot 2 3/4 shells, If The 2 3/4 Inch Load You Intend To Use Would Develop Pressure That Is Safe In That Gun, When Fired In A Standard Chamber!

Prior to the advent of folded crimps, shot shells had rolled crimps. The shell mouth acted as a gasket to both funnel the shot into the forcing cone and to prevent blowby as the fiber and/or felt wad passed the slight, but even constriction. With the advent of folded crimps, shell mouthes were being ripped off and gas was getting into the pattern to a degree. This caused problems of its own.

Member Joined: 25 Jul 2006 Posts: 781

Another reason short shells continued to be made is that there was demand, especially from pump and autoloader owners. Safety aside, their guns would not cycle the longer shells as the mechanisms and ejection ports were not long enough.

Jeff

More pearls from Researcher on the Fox Collectors site:

When Western brought out the Super-X in 16-gauge it came in a 2 9/16 inch case. Up through at least the 1937 Western Ammunition Handbook only 2 9/16 inch hulls are listed for 16-gauge. The next paper I have is 1941. The Winchester Ammunition Guide offers the Super-Speed in both 2 9/16 and 2 3/4 inch. The load in the short case was 3 dram equiv. and 1 1/8 ounces of shot while the load in the 2 3/4 inch case was listed as 3 1/4 dram equiv. and 1 1/8 ounces of shot. By the way Winchester and Western in those days were just the two sides of the same Olin Corporation coin. The Western Ammunition Guide calls the 2 3/4 inch hull 16-gauge Super-X a magnum but doesn't list the dram equiv., but it is still the 1 1/8 ounces iof shot. The 1 1/4 ounce 2 3/4 inch 16-gauge magnum didn't come along until the 1950s.

Remington seemed to be the leader in lengthening the 16-gauge hull. When Remington brought out their Model 11 and "Sportsman" Autoloading shotguns in 16-gauge along about 1931 or 2 they were made for 2 3/4 inch shells and their catalogues stated "..the new 16-gauge Auto Express Shell has been developed for use in this model as well as the Sportsman."

Ithaca first starts listing their 16-gauge NIDs as being 2 3/4 inch chambered in the 1934 catalogues. From 1926 through 1933 they list 2 9/16 inch.

A number of fine guns were made with slightly short chambers right into the 1960's. FN Browning superposed target guns had slightly short chambers. Both Miroku and Kodensa copied the idea on their Superposed knock offs for Charles Daly and the Winchester 101 line respectively. To this day, I don't think the Japanese realized that the FN guns they copied were designed for paper shells with felt and fiber wads. They just copied the guns' dimensions faithfully without question. with the advent of plastic shells and plastic wads, these guns were brutal to shoot an entire match with.

I've owned a number of both these earlier Japanese O/U guns in trap and skeet configurations as well as a few FN Superposed trap guns that would whack you fairly stoutly with one piece plastic wad type ammo. The only cure for the objectionable amount of felt recoil on the earlier ones was both slightly lengthened chambers and cones. The three inch chambered field guns did not recoil nearly as bad.

Miroku started making all its 12 and 20 ga target skeet guns with 3 inch chambers which helped. They also modified the last few runs of the trap models which helped some. The 101 line went to overbored barrels with lengthened cones in its XTR and Diamond Grade target guns towards the end. To this day, many of the old blue model 101 trap sets and skeet guns remain unaltered due to the chrome lined bores and chambers. These guns kick more than others and remain less popular than the field models because of it.