Vintage Shell Pressures

[Drew Hause]

Not sure how I've missed this DuPont Ballistic Table all this time but this should settle some questions; from Parker Brothers “The Small Bore Shotgun” p. 12
http://parkerguns.org/pages/PDF%20Do...%20Shotgun.pdf
p. 7
“All powders referred to on these pages are of the bulk nitro kind ranging from 12 (“New Schultze”, New “E.C. Improved No. 2”) to 13 1/3 (original DuPont Bulk) grains per dram…”
Original “E.C.” and “Schultze” were 14 grains/dram

First published c. 1915 but this appears to be an after 1920 edition
Forest & Stream
https://books.google.com/books?id=lR...J&pg=PA247&lpg

Frank and I were discussing this on another thread, but I couldn't find it.

It is clear that this table converts Long Tons to PSI simply by multiplying by 2240; NOT using Burrard’s conversion.

Compare the 3 Dr. 1 1/4 oz. DuPont Bulk pressure of about 9,600 psi in this 1933 pressure-curve from "Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics" by Wallace H Coxe; E.I. du Pont de Nemours & Co.



The powder appears to be a 36 grain = 3 Dr. Eq. Bulk



These numbers require adding 10 - 14% for modern piezo transducer pressures.

12 gauge
…..3 Dr. Eq. 1 1/8 oz. = 8,110 psi
…..3 1/4 Dr. Eq. 1 1/8 oz. = 8,960 psi
…..3 1/2 Dr. Eq. 1 1/4 oz. = 9,900 psi
16 gauge
…..2 3/4 Dr. Eq. 7/8 oz. = 7,035 psi
…..3 Dr. Eq. 1 oz. = 8,980 psi
20 gauge
…..2 1/2 Dr. Eq. 7/8 oz. = 12,655 psi (that is significantly higher than other reported Bulk and even Dense pressures)

"E.C." and "Schultze" Bulk both ran slightly higher than DuPont Bulk

DENSE Smokeless Powder pressures would be 1000 - 1,500 psi higher

Lots more numbers here
https://docs.google.com/document/d/1...UOZEFU/preview

[Ed Blake]

So if I’m reading that table correctly, a 3 dreq load produces only 900 ft per second? Sounds like bulk smokeless was not very efficient. I think I’ll stick to my ClayDot.

[Cold Spring]

Originally Posted by Ed Blake

So if I’m reading that table correctly, a 3 dreq load produces only 900 ft per second? Sounds like bulk smokeless was not very efficient. I think I’ll stick to my ClayDot.

Period shotshell speeds were given in average velocity over 40 yards. One factor often forgotten when quoting those speeds is the pellet size, as smaller diameter shot will bleed off speed more quickly than larger pellets, and hence different averages for the same drams or drams equivalent loading. Drew's second chart shows 7-shot but often such charts only show gauge, drams or DE, and weight of shot.

Thanks Drew for noting the math conversion, i.e., tons x 2240 = lead units of pressure. If I read again about Burrard's conversion being applied to period American shotshell velocity as measured by lead crushers, I think I'll get into shivers and convulsions.

frank

[Drew Hause]

It is terribly confusing

This is the earliest pressure numbers expressed as PSI in U.S. literature that I have found; in The Overland Monthly, Oct. 1895 “Smokeless Powder For Shotguns” p.453
http://books.google.com/books?id=Wv0...J&pg=PA446&lpg
3 1/4 Dram Eq./40 grains DuPont Bulk Smokeless 1 1/8 oz. (1255 fps) = 7440 psi
3 1/4 Dram Eq./44 grains “E.C.” Bulk Smokeless 1 1/8 oz. = 7584 psi
10-14% for modern piezo transducer numbers

This is a Winchester Factory Memorandum dated February 6, 1900

12g 2 5/8" Leader with 1 oz. shot
40 gr. DuPont Bulk = 3 1/4 Dr. Eq. = 2.7 tons/sq. inch = 7952 psi by Burrard; only 6,650 psi if X 2240 + 10% and that is far below other reported numbers.
The Parker DuPont Ballistic Table lists DuPont Bulk 3 1/4 Dr. Eq. 1 oz. at 3.17 tons = 7800 psi by X 2240 + 10% which seems in keeping with other numbers.
42 gr. Laflin & Rand Bulk = 3 1/2 Dr. Eq. = 3.3 tons = 9968 psi by Burrard; 8,130 psi by X 2240 + 10%.

12g 2 5/8" Leader with 1 1/8 oz. shot
40 gr. DuPont Bulk = 3 1/4 Dr. Eq. = 3.9 tons X 2240 + 10% = 9,600; 11,984 psi by Burrard. The Parker table lists 4.0 tons X 2240 + 10% = 9,850 psi

Either the British and U.S. ballistic engineers were using different Tarage tables, or DuPont was using a PSI Tarage table and simply converting to Tons by multiplying X 2240??

[Drew Hause]

I posted a long summary of 3 Dr. Eq. 1 1/8 oz. Bulk Smokeless pressures here
http://www.doublegunshop.com/forums/...34&#Post525434

[Southpaw]

Dr. Drew you have a staggering amount of material with breadth and depth on this topic. I always enjoy your stuff. Really enjoyed reading that free brochure you linked to on Sunday afternoon. Have also read your papers with keen interest and based on past info these gun barrels have built in superadequacy even if pressures in heavy loads are maxing out at 10K to 12K PSI. Your previous info material on proof tests showed barrels failure point was about 30k PSI.

Taking all this into account do have any thoughts, summary or a reconciliation of what this all means if you had to make an elevator speech on the topic. I know its more complex than that but just trying to get a firm takeaway.

[Carl G. Bachhuber]

When I see these old pressure curves, velocity data, etc. I just have to shake my head. I spent my life as an engineer making things, breaking things, measuring things, and testing things. I just have to wonder how they did it? The first electronic chronographs showed up after the 2nd WW. The strain gauge was invented around 1938. High speed data recording came along in the late 1960's. I wonder if there are any text books from the early 1900's that mention such measurements? That could be some interesting reading. I suspect that a lot of the published data was invented in the ad departments.
C.G.B.

[Drew Hause]

Here you go Carl

British Crusher Gauge illustration
https://books.google.com/books?id=in...AAJ&pg=PA29&dq
Tarage Table
https://books.google.com/books?id=in...AAJ&pg=PA37&dq

Wallace H. Coxe, in “Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics” published by E.I. du Pont de Nemours & Co., 1927, “Measurement of Pressures”
The common method of taking pressures in small arms in this country is known as the Radial Pressure system. A housing is built around the barrel, and a hole drilled through the housing and barrel into the chamber at a distance of 1 inch from the breech and at right angles to the axis of the bore. The hole is then bushed and drilled to a uniform diameter of 0.2250 inch. Then a piston is made the length of the piston hole and 0.2250 inch in diameter. Next the piston hole is lapped to permit the piston to fit snugly without either sticking or getting out of alignment.
In firing the gauge, the piston is inserted and seated, then a lead crusher cylinder is placed on the head of the piston and held firmly in place by a screw and anvil attachment built into the housing. When the cartridge is fired, a portion of the same gas pressure that pushes the bullet through the barrel drives the piston against the lead cylinder and compresses it.
The length of the lead crusher cylinder after compression is naturally less than before the shot was fired and the difference between the original length and the length after compression therefore represents the amount of pressure which has acted upon the lead. Thee exact pressure is read from a table giving a pressure reading for every remaining length reading and commonly called a Tarage Table.
Pressures that are determined at ballistic laboratories are merely relative values and are not absolute values.

NOTE: The Tarage Table conversion may be for pressure expressed as Tons / Sq. Inch or Pounds/ Sq. Inch (PSI).


The Bashforth Chronograph was in general use by the late 1800s
https://archive.org/details/reviseda...shuoft/page/n5

The French used the Boulenge'
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA291

Enter Chronograph in the search box here for lots of historical information
https://books.google.com/books?id=in...gbs_navlinks_s

[charlie cleveland]

drew what would the pressure be in the 3 inch shell with 4 drams of powder and 1 3/8 ounces of shot then what was the pressure of the 4 1/4 drams with 1 5/8 ounce of shot...charlie

[Drew Hause]

Charlie: the 1929 Hunter Arms pressure curve listed the 12g 3" Western 'Record' 1 3/8 oz. shot presumed 1275 – 1295 fps at 13,250 psi + 10-14%