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revdocdrew
PostPosted: Sat Apr 18, 2020 8:12 am  Reply with quote
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Location: Glendale, AZ

Garhart and I were discussing vintage British 16g Rules of Proof and Service Load pressures

Under the 1896-1924 Rules of Proof the 16 bore service charge was 1 oz. 2 3/4 Dram Eq. (1220 fps).
Published pressures:
(2 1/4 Dram C&H Diamond Grain No. 2 Black Powder with 1 oz. shot – 8,860 psi)
Curtis & Harvey's “T.S.” No. 4 BP - 7,480;
“Schultze” - 8,250 psi;
“E.C.” - 8,960 psi
Pressures were measured using crushers (LUP) and reported in pounds/ sq. inch; modern piezoelectric transducer pressures would be 10 - 14% higher.

I don't have specific 16g pressures under the 1925-1954 Rules but this is probably applicable: Major Sir Gerald Burrard, The Modern Shotgun, Volume II, “The Cartridge”, 1955 3rd Revised Edition pressures converted from Long Tons/ Sq. Inch at 1”
Loads were designed for an “observed velocity” - average velocity over 20 yards - of about 1,050 fps = modern 3’ from muzzle velocity of about 1200 fps
Standard Load...…………………..Standard Service...……. Max. Service
16g 2 1/2” 7/8 oz. 2 1/2 Dr. Eq...….8,624 psi...……..…………….11,312 psi
16g 2 3/4” 1 oz. 2 7/8 Dr. Eq...……..9,296 psi...………..………….11,984 psi

John Brindle, author of Shotgun Shooting: Techniques & Technology published a review of Proof and Service pressures in Part 5 of his series in The Double Gun Journal, “Black Powder & Smokeless, Damascus & Steel”; Volume 5, Issue 3, 1994, “Some Modern Fallacies Part 5”, p. 11. His estimated post-1954 but pre-CIP standard pressures by LUP converted to piezo transducer PSI
Standard Service...………. Max. Service
16g 2 1/2” 7,300 psi...………….. 9,300 psi
16g 2 3/4” 7,800 psi...………….. 9,800 psi

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Drew Hause
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Brewster11
PostPosted: Sun Apr 19, 2020 9:42 pm  Reply with quote



Joined: 08 Feb 2009
Posts: 1301
Location: Western WA

Drew
Thank you for the data. Interestingly, those numbers are all over the map. The max service loads for 2 3/4” vary from 9800 to almost 12000. What is one supposed to make of them? You could almost pick whatever number you want and it would be ok. It seems out of character for the Brits to vacillate so much.

V/R
B.
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canvasback
PostPosted: Mon Apr 20, 2020 5:28 am  Reply with quote



Joined: 12 Mar 2012
Posts: 684
Location: Ontario

Everyone needs to make their own informed decisions and do what they feel comfortable with.

When shooting my vintage guns, I start by not trying to cut it too close on MBWT. That includes both the measurable barrel walls as well as possible pits. Basically I don't shoot barrels with pits. And the rest of the barrel walls conform to well established standards throughout their length.

Everything thing I have read over 15 years (and that includes all back issues of DGJ and 11 years of most threads on the DG forums) tells me that most barrel failure in vintgage SxS is the result of obstruction. The few that are not are more often than not likely caused by a accidental overcharge of powder, whether a hand load (mostly) or production.

Once you get past those two causes, it is a terribly infrequent occurrence. I keep my pressures under 8500 psi at the most (and mostly under 7500 psi).

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1921 Pieper 29" 6 lbs 10 oz
2003 Citori White Lightning 26" 6 lbs 10 oz
1932 Husqvarna 310AS 29.5" 6 lbs 7 oz
1925 Ferlach 29" 6 lbs 7 oz
1923 Greifelt 29" 6 lbs 1 oz
1928 Simson 29.5" 6 lbs
1893 Lindner Daly FW 28” 5 lb 11oz
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revdocdrew
PostPosted: Mon Apr 20, 2020 6:28 am  Reply with quote
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Joined: 28 Dec 2005
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Location: Glendale, AZ

One observation is that c. 1900 16g Bulk Smokeless load pressures were very similar to today's, and Dense Smokeless were even higher.

I like Sir Gerald's standard service pressures; assuming the barrels have adequate wall thickness with minimal pitting and the head of the stock wood is without cracks / or (in the case of Long Cracked Smith guns Wink ) has been repaired and glasbedded.

Obviously the loads we would choose for a 16g 870 would not be those we would use in a vintage lightweight 16g game gun, British or otherwise.

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