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Might a generality regarding low pressure loads be established ...

1222 Views 24 Replies 14 Participants Last post by  RMc
... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?
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... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?
Precision Reloading might have an answer for you on that. I once asked them about slower steel target loads and they suggested I try WSF and it worked out great in the tests I had them do. I still use it. Good luck. Interesting concept.
Some things I do know. Low pressure loads use relatively small weights of powder, commonly. They often have problems with wads not being designed to be tall enough to take up the space which a standard powder load would occupy. Low density (fluffy) powders can help take up that additional space.

Even though those stack height challenges may be met, IFAIK, there is no Guarantee that Fluffy powders are more Consistent in pressure and velocity at low pressures. The powders for shotshells are ALL designed to work most consistently in the 9500-11,000 PSI regime.

But, kinda curious why are you trying to establish "golden rules" for shotshell loading, when you don't have 30 or so years of experience and have no equipment for internal ballistics testing, like a dynamic chamber pressure system? Even those with experience are justifiably leery of setting up rules for loading shotgun which might be broken by the NEXT newly developed powder or wad. This isn't metallic cartridge loading where things are fairly predictable.

Just load to published loads. good luck, garrisonjoe
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Payload, charge volume and powder burn rates will have a greater impact on pressures than a generalized rule of thumb regarding powder densities.
I load low pressure (5k psi avg) for 7/8oz 12g/1200fps with Ramshot Competition, which is both a fine grain dense and fast burning powder.

For purposes of comparison between two different density and burn rate powders for the same load, hull, wad and aprox pressure:
Competition 18.2 Grs. 8700psi 1145fps
Longshot 32.2 Grs. 8400psi 1420fps
Too bad Trailboss is unobtainable for a while. It's the rare fluffy powder that ignites with little pressure.
Nothing is more inefficient in burning at a constant rate than a sphere.
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Nothing is more inefficient in burning at a constant rate than a sphere.
Just checked both of the powders I tend to load light and they are tiny little flakes. WSF and TiteWad.
A good source for you to look at would be the Volume Measure Density charts available from both Lee and Hodgdon. They list a large sampling of powders and their densities, good info when looking to potential powder substitutes.

Note that spherical powders are quite common, as are flatted spheres and flake. Just a small sampling of some popular powders:

Longshot - Spherical VMD .0824
Win Sup Fld - Spherical VMD .0840
Competition - Flattened Sphere VMD .1278
Titewad - Flattened Sphere VMD .1300
Red Dot - Flattened Sphere VMD .1413
Green Dot - Flake VMD .1262
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The powders for shotshells are ALL designed to work most consistently in the 9500-11,000 PSI regime.
Have you looked at moderan data, With (we will call it) non legacy powders. Most of the pressures are around 8500-10000. With the majority being less than 9500.
Some things I do know. Low pressure loads use relatively small weights of powder, commonly. They often have problems with wads not being designed to be tall enough to take up the space which a standard powder load would occupy. Low density (fluffy) powders can help take up that additional space.

Even though those stack height challenges may be met, IFAIK, there is no Guarantee that Fluffy powders are more Consistent in pressure and velocity at low pressures. The powders for shotshells are ALL designed to work most consistently in the 9500-11,000 PSI regime.

But, kinda curious why are you trying to establish "golden rules" for shotshell loading, when you don't have 30 or so years of experience and have no equipment for internal ballistics testing, like a dynamic chamber pressure system? Even those with experience are justifiably leery of setting up rules for loading shotgun which might be broken by the NEXT newly developed powder or wad. This isn't metallic cartridge loading where things are fairly predictable.

Just load to published loads. good luck, garrisonjoe
Think I can answer the why......... nothing else better to do, retired, bored, too much time on his hands. Has to have something to post to keep up with Jones.
... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?
7K to 8K is NOT considered low pressure, especially in the 12 gauge. 6K and under would be considered low pressure. 7k to 9K is average pressure and 10K and above is considered by many to be high pressure.
I regularly load 12 ga. 7/8th oz. loads with as little powder as 15.8 grains of Clays (16.5 grains for colder weather), and 13.8 grains of 700X, and 12.9 grains of Extra Light. All of those loads work well in the hull with the 7/8th gray wads and will break 50 yard crossers. They also don't leave much residue in the barrels. I have no idea what the pressures are, but they will cycle my Maxus.

The 700X load chronographs right at 1100 FPS and is my favorite.
... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?
No. Chemical composition introduces too many variables (single base/double base/retardants/etc.)
As far as North American smokeless powder mfg., it was only some of the older (and likely by now discontinued, or likely soon to be discontinued) IMR shotshell powders which were single base. All Alliant powders are double base. All ball powders are double base.

If burn rate is a concern, albeit that this should have been implicit from the onset, then think of this as a case whereby both the flake and the ball sit in very close proximity within the burn rate chart.

Retardants are likely shared in common, albeit that the degree of retardant likely differs from flake to ball for a given burn rate.

But the issue being raised involves the inefficiency of burning a sphere vs. burning a flake. And the contention (prefaced with 'might' as well as with 'generality') is that at low pressures a flake will burn more consistently (with regard to temperature extremes) than will a ball.
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Too bad Trailboss is unobtainable for a while. It's the rare fluffy powder that ignites with little pressure.
Trail Boss is NOT a shotgun powder.
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Trail Boss is NOT a shotgun powder.
Next, you'll be telling me that you can't load a shotgun with black powder or pyrodex!
The topic is "low pressure" and some of us consider shotguns in the 1890-1900 time frame.

If you said "it's not suitable for a progressive press", I would agree with you.
If you said "I don't personally use any loads not tested and published by a factory", that's another thing to say.
If you said "it's not suitable for a progressive press", I would agree with you.
If you said "I don't personally use any loads not tested and published by a factory", that's another thing to say.
There's no such thing as a shotgun powder being suitable or not suitable for a progressive press.

I'm not really sure where that thought originated.

Hodgdon sells Trail Boss and they have no tested data available for shotgun use.

I don't really care if anyone outside of Hodgdon has tested Trail Boss.

Until Hodgdon produces shotgun data for their product, I will not consider it a shotgun powder.

You're quite welcome to view Trail Boss however you choose. :)
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I've re read the OPs post three or four times and I'm not sure what, or why he's asking the question he is. In rifle and pistol you need to be more accurate with your loads than shotgun reloads. So ball powders are used more often because they meter better.
All I know is 800x performed well for me (no especially cold tests) at ~ 7 kpsi (1 oz 12g loads).

It's "fluffy"

It raises hell with sub gauge progressive loaders, though some have been successful.

Ball powder has long been associated with being harder to light effectively.
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