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Apr 27th, 2024
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Joined: Jan 2006
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Sidelock
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Sidelock
Joined: Jan 2006
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Joined: Jan 2002
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Sidelock
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Sidelock
Joined: Jan 2002
Posts: 11,377 Likes: 105 |
Well I thought I would add a bit this evening.
My 20ga damascus Flues gun has a thin spot of .018 @ 16" from the breach in the left barrel. I was really apprehensive about shooting it after this discovery, even with low pressure shells.
So, I figured what the heck, I would blow it up or shoot it. Loaded 4ea. hand loads @ 12,500psi per the IMR manual and did the string/proof/behind the tree test. I measured the barrels at a bunch of points before and after.
All is good.
Carry on. ymmv
Well . . .while you're likely safe with low pressure shells, 12,500 psi represents only a very slight pressure bump over SAAMI's current standard service pressure (max average pressure) of 12,000 psi for the 20ga. SAAMI proof loads run in the 18-19,000 psi range. Someone hearing that Damascus is safe with smokeless powder and not delving into the details might start shooting a bunch of Wal-Mart specials because they're "light loads" . . . and have a very unpleasant surprise.
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Joined: Dec 2001
Posts: 12,743
Sidelock
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Sidelock
Joined: Dec 2001
Posts: 12,743 |
Well I thought I would add a bit this evening.
My 20ga damascus Flues gun has a thin spot of .018 @ 16" from the breach in the left barrel. I was really apprehensive about shooting it after this discovery, even with low pressure shells.
So, I figured what the heck, I would blow it up or shoot it. Loaded 4ea. hand loads @ 12,500psi per the IMR manual and did the string/proof/behind the tree test. I measured the barrels at a bunch of points before and after.
All is good.
Carry on. ymmv
First off let's establish a few facts here. At 16" from the breech those barrels can really care less what the max chamber pressure is. What they are concerned about is what the pressure is @ 16" from the breech. "IF" you take two loads of the same intensity, IE, same shot load fired to same velocity but with widely varied max chamber pressure. It is a Given that forward of the chamber area for the rest of the length of the barrel the load giving the "Low" pressure load will have higher pressures than will the low pressure load. To "Protect" a thin area in the forward 2/3-3/4 portion of the barrel keep your shot load light & velocities moderate. Then load the fastest burning powder that will meet the criteria of desired max chamber pressure commensurate for the barrel mat'l. Assuming that your "Proof" load @ 12,500 psi was done with at least an ounce of shot & used a slow burn powder, then you should be in fine shape with 3/4oz or no more than 7/8oz of shot with a faster powder up to about 9K psi. IF you load 7/8-1oz of shot to a bit more velocity & lower your max pressure by going to a very slow powder you are not doing that thin spot @ 16" any favor.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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Joined: Jan 2006
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Sidelock
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Sidelock
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It'll be a great story to tell your grandkids....
I lost my fingers when the barrel exploded on a 130 year old shotgun that had been modified by some back yard gunsmith.
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Joined: Dec 2014
Posts: 906 Likes: 30
Sidelock
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Sidelock
Joined: Dec 2014
Posts: 906 Likes: 30 |
Miller,
Good morning.
I watch your comments on pressure all of the time and take them to heart.
The load I used was 7/8oz @ 12500psi using IMR7625 a bit over 1200fps. Maybe I'll do it one more time with 800x and 1oz @ 11.6K.
That should keep the pressure up a bit farther out.
My load for the gun uses 20/28 powder, 3/4oz @ 6300psi and 1071fps. Almost no recoil in a sub 6lb gun. A real treat to shoot.
Last edited by ithaca1; 09/15/16 10:55 AM.
Bill Johnson
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Sidelock
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OP
Sidelock
Joined: Dec 2007
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Thank you for the link Drew... unfortunately, the Herter shells, ones I was most interested in, did not have the PSI listed... just my luck! Thanks again Adam
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Joined: Jan 2002
Posts: 13,154 Likes: 1152
Sidelock
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Sidelock
Joined: Jan 2002
Posts: 13,154 Likes: 1152 |
Shoot off five to Tom Armbrust, Adam, and end the speculation once and for all. He could get them done before winter sets in if you sent them soon. He doesn't do any pressure testing once cold weather sets in there.
SRH
May God bless America and those who defend her.
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Joined: Jan 2016
Posts: 94
Sidelock
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Sidelock
Joined: Jan 2016
Posts: 94 |
While I do not yet have a Demarcus gun I am interested in low pressure target and hunting loads for my double guns. I would like to load some low pressure shells using a Remington STS hull, Promo powder, and a Winchester primer. I normally use either 1oz or 1 1/8 oz Claybuster wads. Published information with these components or others would be most useful.
j born
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Joined: Mar 2011
Posts: 4,081 Likes: 472
Sidelock
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Sidelock
Joined: Mar 2011
Posts: 4,081 Likes: 472 |
While I do not yet have a Demarcus gun I am interested in low pressure target and hunting loads for my double guns. I would like to load some low pressure shells using a Remington STS hull, Promo powder, and a Winchester primer. I normally use either 1oz or 1 1/8 oz Claybuster wads. Published information with these components or others would be most useful.
j born Will require you to be more flexible with components but there are several loads here: https://www.nssa-nsca.org/wp-content/uploads/2011/10/ceretto.pdf
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Joined: Jan 2006
Posts: 9,417 Likes: 314
Sidelock
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Sidelock
Joined: Jan 2006
Posts: 9,417 Likes: 314 |
At the risk of repeating myself  or possibly clarifying: Questions 1 through 9 should be what is the minimal wall thickness at the end of the chamber, the forcing cone, and every inch out to 9-12" of my barrels; information that Adam as yet does not have. I've seen dealers quickly run a pin gauge down one side (the thick side) of a barrel, announce the MWT as ___, and pronounce the barrels as "fine". That information is next to meaningless unless the dealer says "oops, the wall thickness at 6 inches is .030". And I am of the opinion that in the absence of cracks in the head of the stock, any vintage gun with adequate wall thickness and tight lock-up can handle 1 oz. at 1200 fps target loads. Even better for boxlocks and farm implement Smiths if the head of the stock has been glasbedded.
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