Powders based on cartridge pressure?

[Shadow9mm]

So based on some recent testing I had question pop up that I had never thought of before.

Note: 44spl loads tested in a 20in barrel rifle, thus the slower burning powders.

While testing some 44spl loads I was advised that H110 would not perform well in a low pressure cartridge, it did not. During testing I found that CFE Pistol performed very poorly in 44spl as well, and it is on the slower side of pistol powders. Both powders are ball powders. Both powders were used with winchester large pistol primers rated for regular or magnum loads. I also tried CFE Pistol in 38spl and got poor results.

I have used CFE Pistol in 9mm and gotten good results, I am wondering if this is due to the higher pressure?

Are some powders better suited to low or high pressure cartridges? If so, which are they? Would one be able to choose an optimal powder based on cartridge or load pressure?

 

[rclark]

Powders always work better at higher pressures. So in low velocity (low pressure) situations, you want to pick a faster powder to keep that pressure up as much as possible (within SAAMI). Take Trail Boss. It's a fast burner and keeps the pressure up with low velocity shooting (like cowboy action). Why it is popular in that situation (being 'bulky' is nice too). But for general purpose better powders like Unique and Power Pistol are generally used. Why? Because you can get to higher velocities easier with these medium burn powders. Hope that makes sense!


I am surprised with your CFE Pistol comments. All my .44 Special tests with it under a 240g SWC are marked as accurate and at the higher velocities Accurate+ . Tested from 6.0gr to 8.5gr. I liked 8.0gr the best which is a 1000fps load out of a 5 1/2" barrel. ES was 20fps across 15 shots. Never tested H110 as it is the wrong powder for .44 Special. Way to slow. Save it for the Magnum.

 

[Shadow9mm]

Powders always work better at higher pressures. So in low velocity (low pressure) situations, you want to pick a faster powder to keep that pressure up as much as possible (within SAAMI). Take Trail Boss. It's a fast burner and keeps the pressure up with low velocity shooting (like cowboy action). Why it is popular in that situation (being 'bulky' is nice too). But for general purpose better powders like Unique and Power Pistol are generally used. Why? Because you can get to higher velocities easier with these medium burn powders. Hope that makes sense!


I am surprised with your CFE Pistol comments. All my .44 Special tests with it under a 240g SWC are marked as accurate and at the higher velocities Accurate+ . Tested from 6.0gr to 8.5gr. I liked 8.0gr the best which is a 1000fps load out of a 5 1/2" barrel. ES was 20fps across 15 shots. Never tested H110 as it is the wrong powder for .44 Special. Way to slow. Save it for the Magnum.

I tested CFE Pistol from 5.7 to 6.7 Your loads are a bit stouter than mine were. but I as also running jacketed not lead. I tried H110 as I was running in a 20in barreled rifle, based on what I was told I did not expect it to perform well. However I wanted to try as it was in a rifle. Which led me to believe it may have to do with the pressure, not the burn rate....

Load data I sourced.
Hodgdon
CFE Pistol start 5.6 Max 6.6 898 fps

sierra
CFE Pistol Start 5.3 Max 6.7 850fps

Lee
CFE Pistol start 5.6 Max 6.6 819 fps

 

[SHR970]

I pointed you to water with specific data. What I didn't ad was Speer #12 data which is in line with what I posted. For your purposes data that is given is data that is to be worked within.


Your gun is rated for 44 Mag. ; higher end loads for 44 Special are just a starting point to your goal.

 

[Shadow9mm]

I pointed you to water with specific data. What I didn't ad was Speer #12 data which is in line with what I posted. For your purposes data that is given is data that is to be worked within.


Your gun is rated for 44 Mag. ; higher end loads for 44 Special are just a starting point to your goal.

True, but we were talking #7 at the time. I am clear on my rating and I will be pushing. What I am trying to understand is why a good amount of a slower burning powder, with a magnum primer, provided less velocity than than what was listed for a 5.6in barrel pistol.

The way it was explained was that the pressure was too low for it to burn properly and it should be saved for full house, high pressure loads.

I had a similar issue with CFE Pistol as well and suspect ts the same problem.

Leading to my question, to what degree does the operating pressure of the cartridge effect the burn of the powder regardless of the burn rate. It is something I have never heard discussed and in doing a few searches I have found little to no information. why are powders classed by burn rates, but not by which pressures they operate at best?

 

[rc]

There are factors that affect which powder is best for a caliber. Pressure is one factor as is bulk density of the powder. Some powders will fill a case at full power, others leave a lot of space because they are too quick and filling the case would blow up the gun. Faster powders are less powder position sensitive. H110 needs to be densely packed and maybe even slightly compressed to work best and be lit with magnum primers. 44 special is a round with a big case that runs at lower pressure. 231, Clays, and Unique are a few that would work better than your current choices in that caliber.

 

[reddog81]

All powders have a range that they work well within. A burn rate chart can help identify powders that might work within the range you are looking at. Using reloading manuals or data from powder/bullet manufacturers to find recommendations is what is generally advised.

Hodgdon lists 20 something powders for 44 special. There’s a reason H110 isn’t one of them. Even in 44 Magnum H110 is for loads on the hot end of the spectrum.

 

[Unclenick]

Note: 44spl loads tested in a 20in barrel rifle, thus the slower burning powders.

I tried H110 as I was running in a 20in barreled rifle

I think you may be laboring under the false impression that a longer barrel lets you take advantage of a slower powder to get more velocity. That is true only when you compare an extremely short barrel to a long one, such as a 2" snub nose barrel to a carbine barrel. But once you get to a 3" revolver barrel, you'll find the same load that gives maximum velocity in the 3" also gives maximum velocity in the 20" carbine barrel or extremely close to it.

As to pressures and clean-burning, the higher the pressure, the faster a powder burns. So, higher pressure is able to burn slow powders more completely during the time the bullet is in the barrel.

 

[GeauxTide]

Having different rifle and revolver loads is a recipe for disaster. Look up Brian Pearce's articles on the 44 Special that will give 1200fps with 240 JHP.

 

[Shadow9mm]

I think you may be laboring under the false impression that a longer barrel lets you take advantage of a slower powder to get more velocity. That is true only when you compare an extremely short barrel to a long one, such as a 2" snub nose barrel to a carbine barrel. But once you get to a 3" revolver barrel, you'll find the same load that gives maximum velocity in the 3" also gives maximum velocity in the 20" carbine barrel or extremely close to it.

As to pressures and clean-burning, the higher the pressure, the faster a powder burns. So, higher pressure is able to burn slow powders more completely during the time the bullet is in the barrel.

So higher pressure allows slower powders more completely.

This again raises the question, why are powders listed by a subjective burn rate, rather than optimal cartridge operating pressures?

And if 44mag operates at 36,000psi and 9mm at 35,000 psi why is h110 not used in 9mm? It should have adequate pressure to burn properly. Is the density to high or low to allow proper case fill?

It seems like there should be a list for each cartridge of the optimal powders from best to worst, based on pressure, speed and load density. Rather than whatever loads the manual has in a subjective barrel length in order of velocity.

 

[reddog81]

There is no set optimal operating pressure. Some people are looking for light recoiling loads, some want the most accurate load for a specific bullet, others want the highest velocity. All will have different “optimal” pressures.

 

[HiBC]

Something to keep in mind that applies to loading revolver cartridges with slower or hard to ignite powders.

A strong crimp is critical. The cylinder chamber is essentially freebore. A primer can uncork the bullet . Then we have cylinder gap. That lets fire and pressure escape. Now lets jump to the forcing cone. More open "freebore".

Nitrocellulose itself is pretty much nitrocellulose. I'm no expert, but its pretty much the same stuff from Bullseye to 4831. (I know,double base is different.)

So the difference(in powders/burn rate) is granule size/shape and retardant. H-110 is little spheres.

Its retardant that makes it slow. Its not easy to light. Picture if you will ,absent crimp,the primer pops the cork/bullet clear to the rifling, a pile of hard to light powder is spewing around in the cylinder as the fire leaks out the cylinder gap.Add to that most revolver cartridges have generous,even black powder sized case volume.

Its much better to build up a good ,hot fire and pressure inside the case,behind the crimp before the bullet exits.

The semi-auto ignition process is somewhat apples vs oranges. Typically efficiently sized case volume,and rifling begins engraving before the bullet leaves the case.
Pressure curve/ignition is more ideal

Generally, loading for revolvers is a bit different than loading for semi-autos.

 

[HiBC]

And if 44mag operates at 36,000psi and 9mm at 35,000 psi why is h110 not used in 9mm? It should have adequate pressure to burn properly. Is the density to high or low to allow proper case fill?

It seems like there should be a list for each cartridge of the optimal powders from best to worst, based on pressure, speed and load density. Rather than whatever loads the manual has in a subjective barrel length in order of velocity.

How do you define "Best"?

The folks who write loading manuals test the loads.
If a powder is just a wrong choice, they don't list it. (Note to those who ask about loads they can't find published anywhere.It might be a clue)

Folks have different priorities. Some folks want accuracy above all else. Some want fire breathing dragon slaying loads, Some want flexibility. Tin can loads to OK deer hunting loads with one powder.
Some folks only want to stock 3 different powders, or, these days, they find an old orange and yellow can of H-870 and the want to know if they can use it in the AR. (No,it would not be a good choice) Some like the economy with accuracy provided by Bullseye. It goes bang and pokes holes. Some don't like the idea of double charges being hard to detect at the visual loading block stage.

There are skills you can develop to interpret published data. Per your priorities,its generally easy to narrow it down to two or three powders to test.

Look for clues like "Hunting load" "Accuracy load" A broad or narrow range of charges. Load density. etc

 

[rc]

An "ideal" powder for a particular cartridge will reach a standard velocity with 100% load density. That means no air space after the bullet is seated. I think if you used H110 in 9mm it would be over flowing before you reached a load that would produce standard speed rounds from a 4 inch barrel because it's too slow to be optimum in that case. 800x works well in 357 but it's hard to meter due to large flake size. Blue dot and Unique are very efficient in 9mm and work good as mid range magnum powders.

Some of the most useful pistol powders are:
Universal Clays
Unique
W231

These will load 32 acp to 454 magnum standard or plinker loads but may not give maxium velocity at safe pressures in magnum class cartridges like 357, 44 magnum and 454 Casull. Will will also not fill a large case to full capacity.

 

[Unclenick]

The problem with H110 in a 9mm is the powder space is so short, the bullet doesn't have to move very far before it doubles the volume behind and that the powder is burning in. In other words, expansion is rapid and the slow powders just can't make gas fast enough to keep up with it. This is part of why it is suited to magnum cases. Expansion is slower in them, even at the same bullet velocity.

The plus side of the short case is the powder has nowhere to go to escape from the primer flame, so there is much less powder position sensitivity in them than there is in a long case like a rifle case, in particular.

 

[jetinteriorguy]

You also have to consider the cost to test all the different things in a particular cartridge bullet combination and who pays for this testing. And it all goes out the window anytime something in the testing system deviates from your actual system.

 

[RickB]

When I was developing loads for .45 Super, I started with Enforcer powder, as it had worked well in 10mm, as had AA #7 for the latter, close neighbors on the burn-rate chart.

Apparently, at the lower operating pressure of .45 Super, compared to 10, Enforcer just didn't work; even with a heavy load that I expected to be close to 1200fps, velocities never much exceeded 1000, even as the load was increased progressively by two grains.
With #7, velocity increases were progressive and predictable, all the way to the max printed load.

 

[MarkCO]

Pressure changes the burn rate of all powders. PV=nRT is still a thing.

There is a dance with efficiency that goes into that as well. A slow powder, with a (relatively) longer time at a higher pressure will burn more completely as opposed to a shorter time. A "fast" powder might be efficient, but when the pressure climbs, they typically develop a pressure spike, which, due to momentum, is wasted (and creates things like excessive bolt thrust and or sticky extraction on autoloaders). Burn efficiency and interior ballistics efficiency are not the exact same thing and one that cartridge manufacturer's and hand loaders need to contemplate. With the development of powders that are less prone to spikes, we also see rifle manufacturers going towards shorter barrels (a good thing).

When accuracy comes in to question related to the OPs question, the goal should be to avoid pressure spikes that waste efficiency and tangentially create larger SDs as well as to avoid excessively slow powders that are near max pressure (of the specific loading, not rated max) when the bullet leaves the barrel. Rapid rises or rapid drops in pressure from the time of ignition until the bullet is a foot or two out of the barrel are the transient conditions we need to avoid to make accurate ammunition. When the slope of the pressure curve is extreme, especially if we are at a knee (rise or drop) then the load lacks consistency. That is what creates the large SDs.

Unfortunately, load data does not tell us these important concepts about knees in the pressure curves. Handloaders don't have a way to instrument their barrels to collect this data. In fact MOST of the manufacturer published data is not derived from test barrels with the level of instrumentation to be able to detect these things. But, the ballisticians at the powder manufacturer's do fundamentally understand these concepts and they tend to use powders where, based on the volume of the cartridge and barrel, they have historical data points that push them to a few powders that should work best.

Over the years, powders that had data for a particular caliber have been removed from subsequent manuals. In some cases, that is because a new blend replaced one that yielded lower velocity...but that old powder might still be more "accurate". Or, the ballistician finally got around to testing a powder.

I use two powders in calibers for which there is no published load data. But I called and talked to the Ballistician in both cases. While they work, and work really well, there is no economic driver that benefits the company from developing the load data. Sad is the case for hand loaders which comprise, relatively speaking, a pretty small segment of the total consumption of powder primers, brass and bullets.

 

[gwpercle]

Pressure is very important when selecting powders .
For the first few years of my 38 special / 357 magnum handgun reloading I tried to get Unique to do everything .
Target loads , mid-range and heavy magnum loads ...but try as I might Unique wouldn't work for light low pressure target loads ...Learned that Unique will not properly burn at low pressure ... I bought a jug of Bullseye and 2.7 grs. and a 148 gr. WC and Wah-Lah I hit the 38 special accuracy jackpot . For 357 Magnum ...2400 was the winning ticket .
Unique is still good for the mid-range loads .
You have to select your powder based on the load pressure and burning rate the powder is suited for ... I learned the hard way !
Gary

 

[Metal god]

I use a lot of CFE pistol and recently bought an 8# jug of it . I can tell you for sure it SUCKS in 44spl pressures . I tried it in 44 mag cases at loads between spl max and mag start charges . Total garbage , soot , smoke and unburned powder . I was hoping to use it for very light 44mag loads but it didn't work out . I do that with 357 , pick a charge above special but below mag start loads and many powders do that just fine but in 44 the CFE pistol did not do well . I was bummed cus I got 8# of it and hoped I could use it in all my handgun cartridges . I like it a lot in 9mm especially with 147gr bullets . Works good in 357 and 158gr bullets as well . I've used it in 45acp and it's OK but not a go to 45acp powder . I bet it would do ok in 38spl pushing 180gr bullet

I bought it to replace HS-6 in my inventory and it's doing that job well . but yes IMHO it needs to be pushed hard like HS-6 does . . It seems to like to be 3/4 to max charges where HS-6 seems to want to be at max or above to really do well . I'd say it's a tic slower burn rate then HS-6 , meters fantastically and meters as good or better then any powder I use . All-n-all is a good general powder if you are looking to get a bit more velocity but below magnum velocities .