doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure vs. Velocity

Stan, I really more meant that modern typically available cheap ammunition is hard on old guns. And there's no way to prevent people from sticking it in a shotgun. The irony of the Nitro was that it's touted as being able to digest all modern 2 3/4 loads.

Mike--Sherman Bell pretty much took the "guesstimating" out of it--although he certainly did not invent the wheel when it comes to longer hulls in shorter chambers. Both Major Burrard and Gough Thomas have pointed out that it is not the length of the shell per se, but rather the pressure the load generates, that causes any danger from pressure. And the Brits themselves have been shooting longer hulls in shorter chambers for decades.

There's not much sense in loading 3" hulls for 2 1/2" guns. 2 3/4" hulls . . . well, that's what we have in this country, for the most part. There's a whole bunch of tinkering involved if you're going to reload 2 1/2" hulls. Meanwhile, all kinds of recipes for 2 3/4" hulls at pressure values well below the service pressure for the guns in question. Makes life much easier if you shoot short-chambered guns a lot and are looking for low pressure loads with light shot charges. And I always tell people that they can just go ahead and shoot RST's, Polywads, foreign 2 1/2" shells, etc. Of course if you're doing a lot of shooting, that very quickly makes the game a lot more expensive. So . . . reloading 2 3/4" hulls to appropriate pressures saves both money and a bunch of tinkering, which equals time. Win/win.

So true, CZ.

SRH

I would like to add two things here & you can take them for whatever they seem to be worth to you.

1st, Stan is 100% correct max chamber pressure has virtually nothing to do with the wood cracking. You can quickly look over a loading manual & find 1oz loads @ 1200 fps which have a higher max pressure than other 1�oz loads @ 1300 fps. You can fire one round of each from a light weight gun & immediatly & distinctively "FEEL" which one is going to be harder on the wood.

2nd is in regards to the long shell/short chamber aspect. Burrard made this very clear many, many years ago. As Larry pointed out its the pressure the shell is loaded to which is of primary importance. There is however one other aspect which is seldom mentioned & this is the "Loaded" length of the shell. The 25 3/4" hull with a fold/pie crimp applied has approximately the same loaded length as the nominally 2�" hull with a roll crimp. In either instance there is a space in the chamber beyond the loaded shell so the crimp can open in its intended fashion. To paraphrase Burrard "NO" shell should be fired if the crimp is pushed/forced into the forcing cone, thus placing a restriction on the opening of the crimp.
I believe this would virtually always apply if a 3" shell was fired from the 2�"/65mm chamber.
Yes, you might do it & not blow up the gun, but "NO" it is not a sound practise.

If you had a handicapped daughter, you wouldn't make her walk to school in the cold, if you had a nice warm car to drive her in.

That is how it is with our old girls.

Ithaca1

Miller, don't you mean if a hull opens in the bore past the forcing cone? Even Parker wanted the hulls to open partially into the forcing cone.

These (monthly) threads are interesting and frequently illuminating. I am neither a metallurgist nor engineer, am a victim of a public education in the great state of Missouri, and have a bit of math LD so am not good with numbers. I only know what I read in (mostly vintage) published literature. So here goes


What Load Should I Use In My Vintage Double?

U.S. Maker�s 12g Hang Tags 1895-1915 usually specified 1 1/8 oz. with 3 1/4 Dram Bulk Smokeless; with published pressures of about 8,500 psi by modern piezoelectric transducer measurement.

Live Bird Competitors routinely used 1 1/4 oz. with 3 1/2 Drams Bulk Smokeless; with published pressures of about 11,700 psi, above the current SAAMI maximum recommended pressure for 2 3/4� 12g loads.

Some competitors choose much higher pressure loads:
DuPont Trophy Oct 24 & 25 1895
http://www.la84foundation.org/SportsLibrary/SportingLife/1895/VOL_26_NO_06/SL2606012.pdf
Capt. John L. Brewer was using a Greener gun of high grade. His shells were the U.M.C. Trap, 3 1/4 inches long, 4 Drams of DuPont (Bulk) powder by measure, weighing 46 1/2 grains; one trap wad, two pink felts, 1/4 inch 11-gauge wad and one ordinary 12-gauge pink edge wad over the powder and 1 1/4 ounces of No. 7 chilled shot.

The 12g Winchester Repeater shells were introduced in 1900 with 1 1/8 oz. 3 Dram Eq. Pressure with Bulk Smokeless powder was less than 8,000 psi; about 10% higher with Dense Smokeless powders (Ballistite and Infallible).
http://www.la84foundation.org/SportsLibrary/SportingLife/1900/VOL_34_NO_23/SL3423013.pdf
This eventually became the standard �Target� load.

Progressive Burning DuPont Improved Military Rifle (I.M.R.) Powders were introduced in 1914. DuPont Oval was 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. The Peters Cartridge Company's �High Velocity�, United States Cartridge's �Ajax Heavies Long-Range�, and Remington's Kleanbore �Nitro Express Extra Long Range� loads soon followed.
Western�s 3 inch �Record� with 1 3/8 oz. of shot was released in 1924; U.S. Cartridge Co. �Climax Heavies� in 1927. Peters also introduced a 3 inch �High Velocity� and eventually the DeLuxe Target 3� with 1 3/8 oz. / 4 Dr. Eq. and 1 5/8 oz. / 4 1/4 Dr. Eq. to compete with the Winchester/Western 1 5/8 oz. 12 gauge 3� magnum introduced in 1935.
In a 1927 Western Cartridge Co. flyer �Super-X The Long Range Load� by Capt. Chas. Askins the 12g duck load is described as 38 1/2 grains or 3 1/2 dram (powder not specified but likely DuPont Oval) with a breech pressure of 3 3/4 tons or about 11,480 psi.

The standard 2 1/2� 12g British load according to the 1907 edition of Greener's The Gun was 1 1/8 oz. 3 1/4 dram (1255 fps).
Major Sir Gerald Burrard in the 1947 Second Edition of The Modern Shotgun, Vol. III �The Gun and the Cartridge�, states during WWI the standard was dropped by law (to conserve the supplies of lead and powder) to 1 oz. 3 dram. After the war, the standard for 2 1/2� shells became 1 1/16 oz. with 42 grains (Old) Schultze Bulk (3 Dram), 36 grains �E.C. (Improved)� or 33 grains Imperial Chemical Industries (Eley & Kynoch Cartridges) Dense Smokeless Diamond powder.
Modern CIP service pressure for 3 Tons / 850 BAR �standard proof� British guns is 10,730 psi.

It would seem reasonable to choose (ballistically similar) loads for which the gun was originally designed.
HOWEVER, bad things happen to shotguns in 100 - 125 years of use. Determining what load YOUR gun should use requires the interest, expertise, and equipment to properly evaluate the barrel integrity (esp. wall thickness), action (esp. lock-up), and wood (esp. cracks in the head of the stock).

Thoughts? Corrections? Opinions (since we all have one, along with other body parts )

To continue with Drew's historical references:

Some of the nation's top trapshooters intentionally used longer hulls in shorter chambers. Those old paper hulls, opening just into the forcing cone, provided some cushioning for the shot in the pre-plastic wad days. They got better patterns. A.P. Curtis, who worked in the US firearms business for over 40 years, wrote a 2-part series in the American Rifleman back in the 30's, touting the BENEFIT of slightly longer hulls in producing better patterns. (Note that those benefits no longer exist--assuming you're using plastic wads, which provide even better cushioning for the shot.)

NO; I meant exactly what I said. The"LOADED" length of the shell should be shorter than the chamber so the crimp can open normally. If the end of the Loaded shell is pushed into the cone the force needed to open the crimp is increased, thus raising the pressure at the initial movement of the shot.
I do definitely agree that no shell should be fired in a barrel with so short a forcing that the hull will open into the bore ahead of it.
This is however I believe a situation which is very rarely encountered, though it can & Has occurred.

It has been suggested that if a plastic case mouth is "feathered", it is evidence of having entered the bore. Can that be confirmed?



I do not have Sherman Bell's "Finding Out for Myself" Part V "Long Shells in Short Chambers" article in Double Gun Journal, Winter 2001. Did he comment? And how many shells did he test please?