Vintage Shell Pressures

[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