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Drew Hause, eeb, Glacierjohn, JNW
Total Likes: 10
Original Post (Thread Starter)
by Glacierjohn
I know we obsess on here and other vintage sites about being extra careful with these old guns as well we should. In particular with regards to using 2-1/2” RST shells in the vintage Parker’s, Foxes and such. What did people do with these guns the 60-70 years before RST existed? I’m guessing they were hunted with regular 2-3/4” off the shelf shells with no issue.

My father in law did that all through the 50s- 70s hunting and shooting a lot of pheasants with his grandfather’s 1889 Parker GH 12 gauge. Even with Damascus barrels he never gave it a second thought and never had a problem.

Now with the low availability of shotgun shells, components and RST shells, I’m tempted to use 2-3/4” shells, and have to confess that I have this season, used them in my 1924 Parker VH. It has the original 2-5/8” chambers but with lengthened forcing cones. It has shot well with low recoil and probably killed 60-70 ducks and 20 pheasants.

Right now I’m looking at a 1928 16 gauge Sterlingworth with original chambers, but I’m worried about the availability of 2-1/2” 16 gauge shells. I have tons of 2-3/4” on hand.
Liked Replies
by Ted Schefelbein
Ted Schefelbein
Neither of the facts you posted relate anything about actual pressure. If you are using off the shelf ammunition, realize you are using stuff that is designed to help dirty autoloading guns run, and the stuff is by no means low pressure.

2 members like this
by KY Jon
KY Jon
Sorry Drew I am not aware of any real numbers. I have seen speculation about this but no real solid numbers. For that reason I have arbitrarily set my maximum 20 gauge classic double pressure level for 20, both short and 2 3/4” at 8,000 psi. From everything I’ve gathered about British proof levels I should be very safe. It is interesting that my Remington 20 empties all measure 2 9/16”. So for compression formed hulls I do use them in my 2 1/2” chambered guns. If loading AA or Federal type hulls I trim them to 2 1/2”. Much easier to find lower pressure loads in Federal or Cheddite type hulls.
2 members like this
by claycrusher1900
For what it's worth, I've fired about 1000 reloads using 2.75" AA hulls (about 2.68" actual measurement) out of my 2.5" chambered 12 gauge. I load them light pressure anyways
1 member likes this
by Ted Schefelbein
Ted Schefelbein
If you load the 2 3/4” hulls to about the same pressure the gun was designed for, you’ll be fine. There is much hand wringing over the length of the cartridge, but, little focus on the pressure they make.

1 member likes this
by limapapa
The consensus on the PGCA website seems to be that Parker cut its chambers 1/8 in shorter than the expected shell length, feeling that the overlap into the cone sealed the shot charge better. Thus, 2 5/8 in chambers were for 2 3/4 in shells. That said, I shoot 2 3/4 shells at 1165 in my 2 9/16 inch 16 gauges without incident. If the barrels are sound, and the chambers original, you should be OK.
1 member likes this
by Drew Hause
Drew Hause
We now have excellent data regarding turn-of-the-century shell pressures, which, with Dense Smokeless, were very similar to today's

Jon: are you aware of any modern pressure data regarding the pressure increase in using long shells in short 20g or 16g chambers?

This is all that I have found, and it's 110 y/o
“The Long 20 Bore Cartridge”, The Field in Forest & Stream, October 17, 1908
2 3/4” case with “Schultze” Bulk Smokeless (42 gr = 3 Dr. Eq.)
The standard 2 1/2” case was loaded with 33 gr. “Schultze” = 2.36 Dr. Eq. (about 2 3/8) with 13/16 oz. shot.
36 gr. = 2.57 Dr. Eq. with 15/16 oz. = 4.65 tons = 14,504 psi (using Burrard’s formula) / 20 yd. velocity 1000 fps. That is the post-1924 Belgian 20g proof pressure.
37 gr. = 2.64 Dr. Eq. with 7/8 oz. = 4.54 tons = 14,134 psi / 1040 fps
35 gr. = 2.5 Dr. Eq. with 13/16 oz. = 3.45 tons = 10,472 psi / 1068 fps

It was Progressive Burning DuPont Oval, developed for the 1922 introduction of Western Cartridge Company’s 12g ‘Super-X Field’ 2 3/4” 1 1/4 oz. 3 3/4 Dram Equiv. shell, that enabled the use of large payloads at lower pressures.
1 member likes this
by L. Brown
L. Brown
Originally Posted by limapapa
The consensus on the PGCA website seems to be that Parker cut its chambers 1/8 in shorter than the expected shell length, feeling that the overlap into the cone sealed the shot charge better. Thus, 2 5/8 in chambers were for 2 3/4 in shells. That said, I shoot 2 3/4 shells at 1165 in my 2 9/16 inch 16 gauges without incident. If the barrels are sound, and the chambers original, you should be OK.

Intentionally short-chambering guns in order to improve patterns was a fairly common practice back when everyone was shooting paper hulls and fiber wads. I have a couple American Rifleman articles from the 30's that discuss it. The author had worked in the firearms industry since the 1890's. He had a 12ga Marlin 90 made with 2 1/2" chambers. Shot patterns using standard 2 3/4" shells. Then had the chambers lengthened and repeated the pattern testing. His patterns ran something like 8% better when using shells that were slightly longer than the chambers. Apparently trap shooters of that era were well aware of that and took advantage of it by making sure chambers were slightly shorter than the length of fired hulls.

Of course today, with plastic hulls and wads that do a better job of protecting the shot charge, there's no advantage to shooting longer hulls in shorter chambers. Nor, however, is there any particular disadvantage . . . AS LONG AS THE PRESSURE GENERATED BY THE LOAD IN QUESTION IS NOT SIGNIFICANTLY HIGHER TO START WITH THAN THE PRESSURE FOR WHICH THE GUN IN QUESTION WAS DESIGNED. The British regularly shoot 67/67.5MM shells in guns with 2 1/2" chambers. It works fine because those shells are loaded to appropriate pressure standards. In contrast, using off the shelf US ammo can be risky because our standard 12ga service pressure is already somewhat higher than the CIP (British/European standard)--by about 800 psi. Add to that the fact that Bell recorded increases in pressure that were mostly only a few hundred psi, although in one case the pressure increased by more than 1,000 psi.

Result: If you're shooting a 12ga and reloading standard American 2 3/4" hulls through a gun in good condition, you shouldn't have a problem as long as you build in a safety margin. It's very easy to come up with reloads, for shot charges up to 1 1/8 oz, at pressures under 8,000 psi.
1 member likes this
by Roy Hebbes
Roy Hebbes
The practice of lengthening the chambers of English guns from 2 1/2 to 2 3/4 accompishes only one thing,It rendered the gun out of proof!
The practice of lengthen chambers dates back to the time when a 2 3/4 shell actually measured 2 3/4, These old shells had card tubes and a rolled turnover.The card tube had a wall thickness greater than todays plastic shells which also possed an increased safety risk if an atempt was made to load them and shoot them in in a 2 1/2 chambered gun!
In reality it was all but impossible to close the action of a 2 1/2 chambered gun with a shell that actually measured 2 3/4 !
It was this issue that prompted ill informed owners to demand that their gunsmiths extend the chamber length of their guns to make them useable!!
The closed length of todays 2 3/4 plastic shells is approximately 2 1/4 inches,after firing it measures approximately 2 5/8 inches.bearing in mind the thin wall of plastic shells and the pressence of a forcing cone from chamber to barrel bore there is virtually no constriction on discharge. I believe it was Burrard that said , "No cartrige case ever caused a barrel failure."
It is the pressure ceated by the weight of the charge &wads in combination with the explosive force of the charge including the the cap, that creates the pressure in the gun barrel
English guns with 2 1/2 inchambers are proof tested at a lower presuure than guns with a 2 3/4 chambers
Those considering extending the length of 2 1/2 chambered gun to 2 3/4 inches ,should ask themseves, Dose removing metal from the barrels of my gun increase their strength or dose reduce the factor of safety?
In 60 years of gun collecting i have seen 100;s of Fine guns put out of proof and in some instances ruined by chamber butchery.
1 member likes this

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