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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%20Documents/Small%20Bore%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 looks to be a second edition after 1920
Forest & Stream
https://books.google.com/books?id=lRMcAQAAMAAJ&pg=PA247&lpg

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 (above the SAAMI recommended maximum and 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/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/preview

William Bruette, Guncraft: Guns, Ammunition, Wing & Trap Shooting, 1912
https://books.google.com/books?id=5g51K93as84C&pg=PA209&dq
Pressures converted from long tons/sq. inch to psi by Burrard�s formula so do NOT require adding 10-14%

Curtis & Harvey�s (42 gr. = 3 Dram) Amberite
12g 2 1/2� case 47 gr. (3 1/3 Dram) 1 1/4 oz. shot = 11,480 psi
12g 2 1/2� case 42 gr. (3 Dram) 1 1/8 oz. = 8,960 psi
16g 2 1/2� case 36 gr. (2 1/2 Dram) 15/16 oz. = 10,640 psi
20g 2 1/2� case 33 gr. (2 1/3 Dram) 13/16 oz. = 11,648 psi

Curtis & Harvey�s Smokeless Diamond (33 gr. = 3 Dram)
12g 2 1/2� case 39 gr. (3 1/2 Dram) 1 3/16 oz. = 11,984 psi
12g 2 1/2� case 33 gr. (3 Dram) 1 1/8 oz. = 9,632 psi
12g 2 1/2� case 33 gr. (3 Dram) 1 oz. = 8,288 psi
16g 2 1/2� case 28 gr. (2 1/2 Dram) 15/16 oz. = 11,480 psi
20g 2 1/2� case 26 gr. (2 1/3 Dram) 13/16 oz. = 12,320 psi

Thanks, Drew. Good information.

SRH

Bottom line is that the pressures for vintage shells were very similar to those of shells today, and in 20g higher.

I noticed on the Parker hang tag, it states; "brass shell should never be used with nitro powder, brass shells may be used with black powder."
Why is that?
Pete

Not 100% sure on this but I think it had a lot to do with available primers of the day. Many of the primers which the brass shells took were sim[ply not hot enough to ignite most smokeless powders. When I began loading shotshells back in the '50's Alacan recommended their brass shells with Berdan primers for use with Dupont Bulk smokeless as well as some loads of Red Dot & an Italian imported Smokeless powder known as Nike. I successfully loaded 20 gauge brass hulls with both. Lyman essentially recommended the domestic brass hulls using large pistol primers for the same powders & stated the Berdan primed brass could be drilled out to take a 209 shotshell primer & be used with the progressive powders. Alcan also imported a line of brass in 12 gauge only as I recall which was made for the Rem #57 primer which could be loaded with the progressive powders.

In all cases when using smokeless it was imperative to get a good Top Wad seal to ensure proper combustion.

To summarize, maybe once and for all

Pressure expressed as (long) Tons/sq. inch as measured by lead crushers (LUP) may be converted to modern piezoelectric transducer PSI using Burrard�s formula
(Cp x 1.5) - .5 = TSI, TSI X 2240 = PSI

Pressure originally expressed a PSI (pound force per square inch) as measured by lead crushers (LUP) requires multiplying by 10 � 14% to reproduce pressure as measured by modern transducers

It appears likely that Wallace H Coxe, ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co., used a PSI Tarage Table (for LUP) and simply multiplied by 2240 for Tons. This would also require multiplying by 10 � 14% to reproduced pressure as measured by modern transducers

SUMMARY OF REPORTED PRESSURES for 3 Dram Eq. 1 1/8 oz. Bulk Smokeless Powders

3 Drams of DuPont FFFg (82 grains) is about 5000 psi.
3 Drams Curtis & Harvey�s No. 4 T.S. (82 grains; somewhat similar but not equivalent to medium grain FFg) was about 6500 psi.

Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in the "Field" Newspaper, Relative to Firearms and Explosives, Volumes 1-2, 1897
�Powder Pressures at Different Parts of the Gunbarrel�
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA32&dq
42 Gr Schultze - 1.69 Tons = 4558 psi by Burrard�s conversion

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA296&dq
�E.C.� � 5,830 expressed as psi + 10% = 6,400 psi
�Schultze� � 6,110 psi + 10% = 6,700 psi

https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA325
42 gr. Bulk (3 Dr. Eq.) � 2.07 tons = 5,835 psi by Burrard�s conversion

G.T. Teasdale-Buckell, Experts on Guns and Shooting, 1900
https://books.google.com/books?id=P7UrAAAAYAAJ&pg=PA235
1 1/8 oz. 42 gr. = 3 Dram Bulk Nitro � 2.71 Tons = 7,985 psi by Burrard�s conversion

Forest & Stream, September 24, 1910 from The Field
https://books.google.com/books?id=mEkcAQAAMAAJ&pg=PA510
42 gr. (3 Dr. Eq.) Schultze 1 1/8 oz. � 3.19 Tons = 9,598 psi by Burrard�s conversion

William Bruette, Guncraft: Guns, Ammunition, Wing & Trap Shooting, 1912
https://books.google.com/books?id=5g51K93as84C&pg=PA209&dq
Curtis & Harvey�s (42 gr. = 3 Dram) Amberite
12g 2 1/2� case 42 gr. (3 Dram) 1 1/8 oz. - 3.0 Tons = 8,960 psi by Burrard�s conversion
Curtis & Harvey�s Smokeless Diamond (33 gr. = 3 Dram)
12g 2 1/2� case 33 gr. (3 Dram) 1 1/8 oz. - 3.2 Tons = 9,632 psi by Burrard�s conversion

DuPont Bulk Ballistic Table c. 1920
3.62 Tons X 2240 - 8,110 psi + 10% = 8,900 psi (11,040 by Burrard�s conversion and obviously not accurate)
http://parkerguns.org/pages/PDF%20Documents/Small%20Bore%20Shotgun.pdf

For Comparison

Winchester Factory Memorandum dated February 6, 1900
12g 2 5/8� Leader case, 1 1/8 oz. with 40 gr. DuPont Bulk = 3 1/4 Dr. Eq. - 3.9 Tons X 2240 = 8736 psi X 10% = 9,600 psi
The c. 1920 DuPont Ballistic Table listed that load as 4.0 tons X 2240 + 10% = 9,850 psi

�Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics� by Wallace H Coxe; ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co., 1927
Charge was 1 1/4 oz. 3 Dr. Eq.
Schultze - 4.5 Tons X 2240 = 10,080 psi + 10% = 11,100 psi
DuPont Bulk - 4.1 Tons X 2240 = 9,184 psi + 10% = 10,100 psi

The 1933 edition of �Smokeless Shotgun Powders� by Wallace Coxe
1 1/4 oz. 3 Dr. Eq. DuPont Bulk - 9,600 psi by LUP + 10% = 10,500 psi

Modern Dense Smokeless Powders in the Alliant 12g Reloading Guide
http://www.alliantpowder.com/reloaders/RecipeList.aspx?gauge=12&gtypeid=3
1 1/8 oz. at 1200 fps (3 Dr.Eq.) in Winchester AA case, Win 209 primer & WAA wad
Unique (�Infallible�) 21 gr = 9,100 psi
Green Dot 19.5 gr = 9,300 psi
e3 17 gr = 10,450 psi
Red Dot 18 gr = 10,400 psi

And some "modern" boomers, from Hunter Arms Co. Pressure Curve dated June 10, 1929, from the McCracken Research Library, Buffalo Bill Center of the West (found by Gary Rennles) and used by permission
http://library.centerofthewest.org/cdm/singleitem/collection/WRAC/id/8149/rec/107

The digital image is part of the Winchester Repeating Arms Company Collection but includes a notation �Hunter Arms Co�. WRAC was acquired by Western Cartridge Co. Dec. 22, 1931, so it is impossible to know if the curve was generated by Winchester, Western, Hunter Arms, or (very possibly) the Burnside Laboratory of the E.I. du Pont de Nemours & Co.

12g 3� �Record� 1 3/8 oz. shot presumed 1275 � 1295 fps = 13,250 psi
12g 2 3/4� �Field� 1 1/4 oz. shot presumed 1330 fps = 10,750 psi
12g 2 3/4� 1 1/4 oz. 28 gr. Ballistite (3 1/2 Dr.Eq.) = 12,900 psi
12g 2 3/4� 1 1/4 oz. 3 1/2 Drams DuPont Bulk = 10,000 psi

+ 10-14%!

Drew;
I note that either 28 grains Ballistite or a 3� dram measure of Dupont bulk smokeless with 1� oz of shot are recommended loads in a 1913 Lefever Arms Co catalog with no mention that they should not be used in their Twist or Damascus barrels.

I would certainly not recommend using such loads in 100+-year-old guns (Steel Barrels Included) & even then not every one loaded this heavy, but obviously, some did or these loads would not be noted.

If you look at it,we need to pay more attention to the first nine inches of the barrels. That�s where all the major pressure occurs. Thin barrels past that become more of a dent risk, than burst risk, without an obstruction.

Been thinking about proper loads for an early 1910-1915 20 ga. pump gun . 2 1/2� is no surprise. But it has Krupp barrels with good wall thickness so maybe pressure is not my major issue. It�s what kind of recoil can the action and stock withstand. Some of these old pump guns don�t have the strongest lockup�s. Food for thought. Maybe a nice 7.5-8k psi load at 1100-1150fps. I suspect original loads for a 20 were greater than that.