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< 16ga. Ammunition & Reloading ~ Why is there a difference in pressure |
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Posted:
Sat Aug 23, 2014 3:43 pm
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Joined: 18 Jan 2013
Posts: 7
Location: Ohio
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Okay, we all know that getting powder is pretty much hit and miss now a days. I've been using 20/28 in RGL for low pressure loads. 20/28 in my neck of the woods is not to be had, so looking for something else.
At the local gun club there is a pretty good supply of Unique so I started searching the spread sheets for loads. I have several hundred once fired Cheddite 2-3/4" red and green hulls so looked in that direction.
I'd like to stay around 1100-1150FPS and 7400PSI or less in a 7/8 to 1 once load of shot. I found these two recipes.
WW poly hulls
19gr. Unique
Win 209
BPI Z16 wad
1156FPS
7300PSI
Cheddite hull
18gr. Unique
Ched 209
BPI SG16
1165FPS
8200PSI
I realize that every component in a recipe makes a difference in the speed and pressure of a load. The spread sheet says that the Cheddite hull can be used in the WW poly hull recipe.
The Cheddite hull recipe makes 900PSI more pressure then the WW poly hull. So, my question is what component do you think is making the major difference in pressure between the two?
Thanks for your input. |
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Posted:
Sat Aug 23, 2014 5:44 pm
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Member
Joined: 12 Mar 2005
Posts: 6535
Location: massachusetts
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The short answer is the two wads are different. Each obturates differently and generates different amounts of resistance to the hull mouths, forcing cones, and the first few inches of the bore. So each wad generates more or less average peak and residual pressures.
Regardless of all this, you may not find Unique to shoot very cleanly at peak pressures under 9200 PSI. However, if your gun has been designed to handle modern ammo, then there are no benefits to be gained from shooting low pressure loads. |
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Posted:
Sat Aug 23, 2014 7:25 pm
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Joined: 18 Jan 2013
Posts: 7
Location: Ohio
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Thanks for the response.
I enjoy shooting my vintage doubles with damascus and twist steel barrels. Naturally the barrels have been checked for soundness and wall thickness. So with shooting low pressure loads in these shotguns, I'm used to slightly dirty barrels.
My next question would be, if the Cheddite hull was used with the WW poly hull recipe would the pressure and velocity of the WW poly hull be maintained?
BTW, do you ever get up around Barre MA.? |
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Posted:
Sat Aug 23, 2014 8:49 pm
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Member
Joined: 08 Nov 2005
Posts: 3438
Location: Illinois
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A good supply of Unique Where in Ohio and what are the prices?--thanks |
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Posted:
Sun Aug 24, 2014 10:24 am
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Member
Joined: 16 Jan 2006
Posts: 1008
Location: Sandy Lake, PA
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16gaugeguy wrote: |
The short answer is the two wads are different.
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An equally short answer is the primers are also different. |
_________________ ------------
Davy 03C&R FFL |
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Posted:
Tue Sep 09, 2014 12:07 pm
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Joined: 07 Sep 2014
Posts: 419
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The 5th Addition of the Lyman Shotshell loading manual shows as much as 32% difference in pressure with the same hull, the same power and the same wad. Only a change in primer.
One of the reasons that I am not loading much lately is that I will not vary from recipe and getting all the different components is not that easy these days as everyone knows.
Bob |
_________________ Robert Kittine
Sag Harbor and Manhattan, New York
WA2YDV
16 Gauge O/U Browning 525 Sporting
16 Gauge SxS Rizzini Islide
16 Gauge Pump Browning BPS Upland
16 Gauge Semi-Auto Remington 1100 Sporting |
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Posted:
Tue Sep 09, 2014 12:39 pm
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Member
Joined: 09 Jan 2013
Posts: 2169
Location: Florida
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rkittine wrote: |
The 5th Addition of the Lyman Shotshell loading manual shows as much as 32% difference in pressure with the same hull, the same power and the same wad. Only a change in primer.
One of the reasons that I am not loading much lately is that I will not vary from recipe and getting all the different components is not that easy these days as everyone knows.
Bob
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Which load ? |
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Posted:
Tue Sep 09, 2014 1:57 pm
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Member
Joined: 29 Mar 2005
Posts: 333
Location: Central Florida
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16gaugeguy wrote: |
The short answer is the two wads are different. Each obturates differently and generates different amounts of resistance to the hull mouths, forcing cones, and the first few inches of the bore. So each wad generates more or less average peak and residual pressures.
Regardless of all this, you may not find Unique to shoot very cleanly at peak pressures under 9200 PSI. However, if your gun has been designed to handle modern ammo, then there are no benefits to be gained from shooting low pressure loads.
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Some benefits to be gained from shooting low pressure loads quite often is a more evenly distributed pattern, less holes and fliers, and less recoil.
xvigauge |
_________________ "Terror lies not in the bang, but in the anticipation of it."
Alfred Hitchcock |
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Posted:
Tue Sep 09, 2014 3:50 pm
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Joined: 07 Sep 2014
Posts: 419
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The comparison is in the Primer Section in the front and not in the list of loads. I do not have the book in from of me, so I can not comment on the Hull, Wad, Powder and shot weight, but they showed all those things staying equal and a number of different primers and the lowest to highest pressure with only a primer change was 32%.
Bob |
_________________ Robert Kittine
Sag Harbor and Manhattan, New York
WA2YDV
16 Gauge O/U Browning 525 Sporting
16 Gauge SxS Rizzini Islide
16 Gauge Pump Browning BPS Upland
16 Gauge Semi-Auto Remington 1100 Sporting |
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Posted:
Wed Sep 10, 2014 2:40 am
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Member
Joined: 09 Jan 2013
Posts: 2169
Location: Florida
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Posted:
Fri Sep 12, 2014 6:59 am
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Joined: 03 Feb 2008
Posts: 830
Location: Adirondak Mtns
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"No benefits to shooting low pressure loads. " I've have always (maybe mistakenly) equated lower pressure with lower recoil. Not so??
Joe
[quote="16gaugeguy"]The short answer is the two wads are different. Each obturates differently and generates different amounts of resistance to the hull mouths, forcing cones, and the first few inches of the bore. So each wad generates more or less average peak and residual pressures.
Regardless of all this, you may not find Unique to shoot very cleanly at peak pressures under 9200 PSI. However, if your gun has been designed to handle modern ammo, then there are no benefits to be gained from shooting low pressure loads.[/quote] |
_________________ Interested in older US made SxS and upland hunting. New to reloading shot shells and looking for info and advice. |
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Posted:
Fri Sep 12, 2014 9:09 am
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Member
Joined: 09 Dec 2005
Posts: 989
Location: Las Vegas
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Somebody may correct me here but I don't believe pressure is a factor when considering recoil. Recoil is determined by payload, velocity and gun weight.
Low pressure is good for old gun metal parts.
Low recoil is good for old gun wood and old farts shoulders.
Matt |
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Posted:
Sat Sep 13, 2014 6:27 am
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Joined: 03 Feb 2008
Posts: 830
Location: Adirondak Mtns
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I certainly qualify for the old fart part of the equation. My thinking ( again maybe flawed) is that with the same pay load lower pressure results in less velocity and less recoil. Would sure like to know if my thinking is correct.
Regards
Joe |
_________________ Interested in older US made SxS and upland hunting. New to reloading shot shells and looking for info and advice. |
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Posted:
Sat Sep 13, 2014 6:45 am
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Member
Joined: 01 Jul 2013
Posts: 324
Location: Brookville , Pa
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Pressure has no effect on recoil . Recoil is only effected by ejecta mass , velocity and gun weight. |
_________________ There's magic in a good , old honest shotgun . Give me a gun with a little character , and I'll try to honor it's history . |
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Posted:
Sat Sep 13, 2014 8:38 am
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Member
Joined: 27 Dec 2005
Posts: 582
Location: Great Lakes
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Is there not some misunderstanding due to most common scenerio being when all components are same, but higher pressure also results from more powder being added to get higher velocity, thus causing more recoil? A "chicken or egg" situation? |
_________________ A Springer Spaniel, a 6# double and a fair day to hunt. |
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