Gas: Extruded vs Spherical

[deadduck357]

Same gun, same case capacity. Will a spherical with a slower burn rate (A2230) produce more gas than an extruded with a faster burn rate (H322) ?

 

[Bart B.]

I would ask the powder company folks.

 

[snert]

And I thought this was an indigestion question//

 

[MagnumManiac]

A generalisation regarding powder burning can be described as this;
a single base powder releases it’s gas at a hotter flame temp with less energy than does a double base powder that releases it’s gas at a cooler temp but releases more energy. It burns more vigorously in other words. Double base powders release gas quicker than single base powders do.
A ball powder burns much cooler than an extruded powder in the same or slower burn rate DEPENDING on cartridge being used. Burn rates are NOT CONSTANT. It changes with bore size, case size and case shape.

Cheers.

 

[KevinThomas]

Same gun, same case capacity. Will a spherical with a slower burn rate (A2230) produce more gas than an extruded with a faster burn rate (H322) ?

You’re asking about totally different powders here, so some of this is probably not prcisely what you’re asking, but burn rate between like powders really makes no difference. If you’re talking about a family of powders, say, IMR4198 and IMR7828, there’s virtually no difference. They’re chemically identical, aside from some very minor differences in deterrent coatings, and so on. When ignited, they’ll produce the same amount of energy, the same amount of gas, just at a vastly different rate. That rate of release is governed by powder geometry and deterrent coatings, but the base make up of th nitrocellulose is identical in both.

In most instances, you’ll find that extruded powders are single-based powders (nitrocellulose), while most ball powders are double-based (nitrocellulose and nitroglycerine), so there’s inherently different levels of chemical energy stored in each, even if we’re talking about the same charge weights. You’re basically comparing apples and oranges here, and would need to do a more in-depth powder to powder comparison, not an across the board generalization. Hope that helps, not sure if it does!

 

[deadduck357]

Testing today got me the answer to my question.

 

[MagnumManiac]

KevinThomas,
There is just as many extruded powders that are double base as there are single base powders.
Alliant powder is double base, Vhit powder in the N series are double base, and no, their makeup is different between burn rates, even though burn rate is essentially irrelevant since no standard is used to garner this info.
What IMR rate their RQ (relative quickness) average, or middle burn rate powder as 100, which in fact is IMR 4198, does not mean that ADI rates H4198 as their RQ of 100. It can be, and is vastly different between manufacturers of which of THEIR powders is used as the baseline to work off in RQ differences.
Companies keep their recipes close to their chests, and general statements regarding burn rate is all that can be made.
Many powders switch their burn rate depending on the cartridge in question, so even this can change how the gas is released. All powders burn in a way where more pressure causes faster gas release and therefore more pressure, which causes even faster burning, and so on and so forth until it is all consumed.
The difference between IMR4198 and IMR7828 is not just coatings etc, it is the amount of nitrocellulose in each kernel due to the size difference, 7828’s flame propagation is probably half that of 4198 or less.
Sorry, but your statements regarding different powders being similar are far from accurate.

Cheers.

 

[bsekf]

Say What????

Single base powder burns hotter than double base powder.
Extruded powder burns hotter than ball (spherical) powder.
Double base powder releases it’s gas at a cooler temp but releases more energy.
DO I HAVE THAT RIGHT!!!
SO
To extend throat life we want to use a double base ball powder.
OK
Is there a list?

Bill "too soon old, too late smart"

 

[Bart B.]

Burn rate table in this link shows one opinion for burn rates:

https://wwpowder.com/resources/data-sheets/

Heat index from Quickload

 

[243winxb]

Is there a list?

Look up the sds or msds of the powders.

Like here https://imrpowder.com/resources/safety-data-sheets/

More then you may want to know about powders here http://www.firearmsid.com/Feature Articles/McCord_gunpowder/

Find photos of powder and type with chemicals here http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=92

 

[louielouie]

I've wondered about the same question as the OP for some time: in the case of the 300 Blackout where there is a narrow range of powders with suitable burn rates, a handful are spherical with a higher loading density and some small kernel extruded powders that may not be as dense when loaded in the same volume but similar weights.
The volume of gas necessary to push the bullet out the barrel AND cycle the BCG reliably with heavy subsonic bullets (jacketed or cast) is what *I'm* reading in the OP's question.

 

[243winxb]

Looking at Barts Quickload chart temperatures for IMR powders , in the same "family" , makes it even more confusing.

https://imrpowder.com/resources/safety-data-sheets/

Faster 4198 should be hotter then 4895?

 

[243winxb]

AND cycle the BCG reliably

In ARs , port pressure is what works the action. Fast burn rate powders may peek to fast with some combinations of bullet & powers.

An adjustable gas block may be useful.

Port size is another variable.

 

[Bart B.]

Port size is another variable.

7.62 Garand barrels were originally the same as 30-06 ones at .079". Quickly opened up to .1065" because 42 grains of IMR4895 in 7.62 match cases didn't produce port pressures as much as 48 grains in 30-06 match cases with smaller ports. Both producing 50,000 cup in chamber with 173 grain bullets.

 

[deadduck357]

I've wondered about the same question as the OP for some time: in the case of the 300 Blackout where there is a narrow range of powders with suitable burn rates, a handful are spherical with a higher loading density and some small kernel extruded powders that may not be as dense when loaded in the same volume but similar weights.
The volume of gas necessary to push the bullet out the barrel AND cycle the BCG reliably with heavy subsonic bullets (jacketed or cast) is what *I'm* reading in the OP's question.

I'm not working with he 300blk but yes this is close to what I was asking.

 

[deadduck357]

In ARs , port pressure is what works the action. Fast burn rate powders may peek to fast with some combinarions of bullet & powers.

An adjustable gas block may be useful.

Port size is another variable.

This is what my testing results showed. H322 would eject the cases but no matter barrel port size would it allow to lock open on bolt, would only push bcg back far enough catch on the carrier. So tried A2230 and locked on bolt first shot.

So results showed faster extruded couldn't sustain enough pressure/gases to function whereas the slower spherical could. Now this is with a rifle length barrel and gas system. Results could be different with a longer barrel or a shorter gas system allowing more dwell time. But from what I'm seeing faster extruded is petering-out sooner and not sustaining enough gases to function (at least in my barrel and gas length).

 

[jepp2]

This is what my testing results showed. H322 would eject the cases but no matter barrel port size would it allow to lock open on bolt, would only push bcg back far enough catch on the carrier. So tried A2230 and locked on bolt first shot.

But you do realize there are sooooo many variables that "could" explain the difference in the carrier locking back, or not, right? So without knowing more about your loads and velocities (and pressures achieved) your conclusion might be flawed. Just for fun, I ran both of the powders in QL, with equivalent peak pressures, and you can see how the two compared.

 

[rogn]

Dont forget that the temperature of the "smoke" has a lot to do with the resulting volume. I think your real question and real answer are what relative volumes of gas are produced by equal masses of representative powders when they are "burned" in a testing "bomb"( closed vessel that the powder can be consumed in and retain the resulting gases ad the temperature and pressure of each can be measured). Burning rates and pressure curves are different questions.

 

[deadduck357]

But you do realize there are sooooo many variables that "could" explain the difference in the carrier locking back, or not, right?

So without knowing more about your loads and velocities (and pressures achieved) your conclusion might be flawed.

Totally agree; case volume, bullet weight, buffer weight, buffer spring, bc weigh, gas system and barrel length can be contributing factors.

With my firearm's set-up I can't see my "conclusion might be flawed". With everything else being the same a change to a slower burning spherical made all the difference from not enough to success.

 

[deadduck357]

I think your real question and real answer are what relative volumes of gas are produced by equal masses of representative powders

Exactly!

But without the knowledge or means it was just left up to field testing lol.