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Sidelock
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We are fortunate today to have an abundance of turn-of-the-century pressure data, which can be found here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/edit

I stumbled upon another interesting source; “Shotgun Ballistics”, Charles Askins, Outdoor Life, July 1917
https://archive.org/details/sim_outdoor-life_1917-07_40_1/page/76/mode/2up

Pressure X 2240 converted to PSI (not Burrard's formula and I am confident that is how DuPont did it), which requires adding 10-14% for modern piezo transducer numbers.

Note modern SAAMI standards allow +/- 90 FPS and +/- 900 PSI = .4 Long Tons

12g 2 3/4” 1 1/8 oz.
……...…………...3 Dram…..3 1/4…..3 1/2…..3 3/4…....4
DuPont Bulk…...7,750……7,840….8,019…..9,744….10,640 PSI
“Schultz” Bulk…8,064……8,960….9,520…..9,878….9,744 PSI

[Linked Image from photos.smugmug.com]

16g 2 7/8” 1 oz.
………...……….2 1/2 Dram…..2 3/4…....3…....….3 1/8..…..3 1/4
DuPont Bulk….7,683…….....8,243..…9,223......9,811…..10,080 PSI
“Schultze”…….8,333…………9,677..…10,461..…12,790..…11,200 PSI

[Linked Image from photos.smugmug.com]

20g 2 7/8” 7/8 oz.
………….…...…..2 1/4 Dram…2 1/2…....2 3/4…..3
DuPont Bulk……10,685…..…12,208..…12,902…14,538 PSI
“Schultze”………11,715...…12,499…..12,858…13,530 PSI

Note the maximum pressure observed for the standard 7/8 oz. 2 1/2 Dram “Schultze” load was 13,978 PSI + 10-14% is approaching proof load pressure at > 15,500 PSI

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Thank you for posting this! The black powder pressures in comparison to the Smokeless are interesting considering, I assume, quite a few older guns would have been fielded using the "new" loads. I know my one uncle used a Damascus barreled Baker 12 gauge up until he died in 1986, his shell of choice was the Winchester Super X 1&1/4 ounce loads. I don't know the pressure of those shells and that may have changed since? The gun was choked full in both barrels. Thanks again.

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Now if we could only get current shotshell companies to cough up their pressures?

Serbus,

Raimey
rse

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liverwort:
The 1928 edition of “Smokeless Shotgun Powders” by Wallace Coxe, ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co. reported 3 1/2 Dram Eq. 1 1/4 oz. loads:
NOTE: pressures were measured by crushers (LUP) and modern transducer measurement pressures would be 10 – 14% higher
DuPont Bulk smokeless powder - 11,700 psi
Schultze Bulk smokeless powder - 11,800 psi
28 grains of Ballistite Dense smokeless powder - 12,600 psi
(Note all 3 are greater than the SAAMI 12g 2 3/4” recommended maximum pressure of 11,500 psi)
40 grains of DuPont Oval Progressive Burning powder used in the Super-X loads - 9,400 psi

There is a Hunter Arms Co. Pressure Curve dated June 10, 1929, from the McCracken Research Library, Buffalo Bill Center of the West (found by Gary Rennles) very likely from DuPont
http://library.centerofthewest.org/cdm/singleitem/collection/WRAC/id/8149/rec/107
12g 3” ‘Record’ 1 3/8 oz. shot presumed 1275 – 1295 fps = 13,250 psi
12g 2 3/4” Super-X ‘Field’ 1 1/4 oz. shot presumed 1330 fps = 10,750 psi
12g 2 3/4” 1 1/4 oz. 28 gr. (Dense) Ballistite = 12,900 psi
12g 2 3/4” 1 1/4 oz. 3 1/2 Drams DuPont Bulk = 10,000 psi
+ 10-14%

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Originally Posted by ellenbr
Now if we could only get current shotshell companies to cough up their pressures?

Serbus,

Raimey
rse

I suspect they prefer to be vague about pressure to allow for lot to lot variances in pressure, all the way up to SAAMI maximum. The only guys who care about pressure, are us, and we won’t be around forever.

Best,
Ted

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Originally Posted by ellenbr
Now if we could only get current shotshell companies to cough up their pressures?

Serbus,

Raimey
rse

Pretty simple to send 5 to Tom Armbrust to determine the pressure(s). 'Twould be nice to get chamber pressures for free from the shotshell manufacturers but, peace of mind is worth far more than Tom's fee, sometimes.


May God bless America and those who defend her.
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Originally Posted by Stanton Hillis
Originally Posted by ellenbr
Now if we could only get current shotshell companies to cough up their pressures?

Serbus,

Raimey
rse

Pretty simple to send 5 to Tom Armbrust to determine the pressure(s). 'Twould be nice to get chamber pressures for free from the shotshell manufacturers but, peace of mind is worth far more than Tom's fee, sometimes.

Which, will tell you the average pressure of five rounds from THAT LOT. The next lot, or the lot produced just before, may have different components and/or powder, and may test completely differently, and as long as they do not exceed SAAMI max, will be considered by the producer to be compliant. If anything at all changed, the pressure can be assumed to be different. But, you have no way of knowing how or which way different, much less what components were changed.

I don’t actually have a dog in this fight, but, we do have to consider US production ammunition suspect, from the standpoint of pressure, unless it is specifically stated on the package.

Best,
Ted

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Agreed, Ted. But, isn't it still better than the current alternative?


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Originally Posted by Stanton Hillis
Agreed, Ted. But, isn't it still better than the current alternative?

No.

If you are a guy shooting one of those guns with .018 wall thickness, 9” from the breech, (or, actually having a dog in that fight) you really have to know what your pressure is. Every time. Yes, there were guns produced with tubes that thin that are in proof. None are mine, however. Too big a feet for that in my world.

The last lot you had tested, is not the same lot they are loading. They are different. That is why they have different lot numbers. Simple as that. SAAMI framework allows for a wide variation of pressures to be sold. The guy with an auto or pump doesn’t know, or, need to know pressure.

Old double gun guys, different deal. I probably should not have posted “US produced” ammunition, above, rather, I should have typed “SAAMI Compliant ammunition”. I have no idea if SAAMI spec ammunition is produced outside the US, or, if it will be, someday.

[Linked Image from i.ibb.co]

Best,
Ted

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Ted, there IS no way to know your pressure everytime, even with RSTs or handloads. Variations in wad seating pressure, powder drop, crimping, even hull to hull plastic elasticity all will affect pressures. The best low pressure reloads that can be turned out have variations in pressure, sometimes significant. I have proven that with loads sent to Tom for testing. But, by having them tested you CAN get your loads within an acceptable range, or determine if factory loads are within an acceptable range. B & P Comp One loads are claimed to be in the 8000 psi range, by the manufacturer. Tom's testing for me has proven that to be true.

I accept pressures in the 8000 range as fine for my Foxes, Parkers, and other vintage guns, even sound Damascus. You may believe differently, and that's fine, but no way do I believe the variation, lot to lot, of this load will yield pressures that get close to SAAMI max, or enough to be a problem.

I don't shoot guns with barrel walls as thin as .018", there's too many fish in the sea. My point in advocating pressure testing of factory loads, to satisfy one person's curiosity, was/is not to try to find some factory loads that can be used in a .018" MWT barrel. You misunderstood my intent, obviously. My wife says I often do not make myself clear on a subject. Perhaps .......

P.S. Tom's testing data shows you more than the AVERAGE pressure for 5 loads, it shows you EACH load's pressure, and the standard deviation, high, and low pressures are determined from that. Much more information on the data sheet than just average pressure for the five loads.


May God bless America and those who defend her.
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