Do double-based powders operate at lower pressures than their single-based counterparts? Some of the data seems to suggest this. Any comments or explanations would be welcome. Thanks.

I always look at powders as to the burn rate slow to fast.
the construction of the graines, determine to some extent how fast or slow they burn or ignite.
pressure would be determined from the cartrage type and of chambering. there are other factors as well.

True enough but it seems that for a given velocity the double-based powder gets you there with lower pressure. At least it seems that way to me from reading perhaps one too many load data charts...

do you have some examples?
i do not see what you are refering to.

quote:

Do double-based powders operate at lower pressures

No.

quote:

Originally posted by hivelosity:
do you have some examples?
i do not see what you are refering to.

Sure. Pull up virtually any one of the examples posted on this page and compare them on a velocity-by-velocity basis. In other words, it appears that for a given velocty the double-based powders come in at a lower pressure. Compare, for example, 180 gr bullets using 4831 vs RL22.

http://forums.accuratereloadin.../2511043/m/316101735

OK I see said the man.
I think it could be the testing its self.
It would be hard pressed to say its the diffrence between single or double based powders.
There may be some connection of powder and pressure according to his testing procedure.

quote:

180 gr bullets using 4831 vs RL22.

You lost me. RL22 is a slower powder than 4831. Provided you have a large enough case capacity it is more than likely you will be able to get enought extra RL22 in the case to reach a higher velocity.

Double base does burn hotter.

DBP have a more energy.

quote:

Originally posted by ramrod340:

quote:

180 gr bullets using 4831 vs RL22.

You lost me. RL22 is a slower powder than 4831. Provided you have a large enough case capacity it is more than likely you will be able to enought extra RL22 in the case to reach a higher velocity.

Double base does burn hotter.

Ok then, compare 4831 to RL19.

quote:

Ok then, compare 4831 to RL19.

I've always found Double based powders burning hotter and providing just a touch more energy. Something like RL22 has always given me close to my maximum velocities in 06 based and reqular magnum cases.

In the for what's worth department. QL says.

With a 180gr accubond 59.8grs of H4831 gave a velocity of 2827. Pressure was 59997(trying to get as close to 60,000 as possible.)
Burn rate for H4831 is .4301 with heat of
explosion of 3870kj/kg in the system.

RL 19 58.75grs gave 59958psi and velocity of 2923 burn rate is .4500 with heat of explosion of 3980.

Tells me RL19(at least in the QL system) burns just a touch faster but also has more energy per kg.

So don't know about the lower pressure. I simply feel(can't find my reference) the DB powders give a touch more energy per gr the trade off is higher temperature.

DBl. Base smokeless powder posses more energy than single base powders .

Page 263
http://books.google.com/books?...#v=onepage&q&f=false



When ignited in an unconfined state, smokeless powder burns inefficiently with an orange-colored flame. It produces a considerable amount of light brown noxious smelling smoke. It leaves a residue of ash and partially burned powder. The flame is hot enough to cause severe burns.

The opposite is true when it burns under pressure as in a cartridge fired in a gun. Then it produces very little smoke, a small glow, and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure.

Ramrod, thanks for running the Quickload data.

In your example for equivalent pressures RL19 had a 100 fps advantage over H4831. I think of H4831 as considerably slower than RL19 but I'm willing to concede that point if necessary. Nevertheless, RL19 gave an additional 100 fps. Run them both for the same velocities and compare pressure and I think you'll find that RL19 comes in lower.

I know double-based powders have more energy due to the addition of nitro-glycerin (sp?); that is not the question. Rather, the issue is, it seems to me that double-based powders provide the same velocities as single-based powders of similar quicknesses, but do so at lower pressures. I've never gotten anyone to agree to that, yet it seems the data supports it.

quote:

In your example for equivalent pressures RL19 had a 100 fps advantage over H4831. I think of H4831 as considerably slower than RL19 but I'm willing to concede that point if necessary. Nevertheless, RL19 gave an additional 100 fps. Run them both for the same velocities and compare pressure and I think you'll find that RL19 comes in lower.

RL19 simply using the burn rate data in QL RL19 is 1/4 the way towards H4350 from H4831.

As to the other comment. If at equal pressure RL19 is 100fps faster it stand to reason that at equal velocity RL19 pressure will be lower.

To me it is basically saying the same thing. In this case you can either have equal pressure and higher velocity or equal velocity and lower pressure.

Since you take them both up to a max pressure load how is one operating at lower pressure? There is a good chance that at equal pressure you will have slightly higher velocity from the DB you will also have higher temp.

quote:

Double base powder produces higher velocity at lower pressure, OK? How is that an advantage to you or us? Higher velocity at lower pressure does not automatically add up to accuracy

Don't know that it is of any major advantage to many. What I have found that since they often provide me a little higher velocity potential I stand a better chance of finding an accuracy load in the velocity range I looking for.

For my medium caliber PDK wildcats MRP or RL22 have always been my go to powder. For my larger bore I look to RL15 it seems to give me higher velocity equal accuracy and less sensitive than something like 4895.

I happen to use more DB than single. But since I'm looking for accuracy and velocity I don't run them at low pressure.

Ther is a trade off in my mind they at least seem to operate at a higher temp. No fancy test just the feeling that they heat my barrels up QUICKER than single based.

quote:

Originally posted by Jim C. <><:

quote:

Do double-based powders operate at lower pressures

No.

simple question.....simple answer.....

Ramrod, if it's beating a dead horse than why do you keep beating it?

Vapodog, maybe the answer is that you're simply ignoring the data.

quote:

Ramrod, if it's beating a dead horse than why do you keep beating it?

I'm sorry I was simply trying to understand and answer your question. I have no further comment believe whatever you want.

quote:

Originally posted by ramrod340:

quote:

Ramrod, if it's beating a dead horse than why do you keep beating it?

I'm sorry I was simply trying to understand and answer your question. I have no further comment believe whatever you want.

It's both amazing and funny when guys post a question to the board that they already have their mind made up on.

Way to work ramrod ....

quote:

Originally posted by rcamuglia:
It's both amazing and funny when guys post a question to the board that they already have their mind made up on.

Way to work ramrod ....

If one can't find the time (or is it mentality) to listen to Ramrod340, well he needs a bit of lecturing.

The Manufacture of Smokeless Powders and their Forensic Analysis: A Brief Review Click link for photos and charts http://www2.fbi.gov/hq/lab/fsc...april2002/mccord.htm Introduction

Smokeless powders are a class of propellants that were developed in the late 19th century to replace black powder. The term smokeless refers to the minimal residue left in the gun barrel following the use of smokeless powder. In forensic analysis, smokeless powders are often encountered as organic gunshot residue or as the explosive charge in improvised explosive devices.

All smokeless powders can be placed into one of three different classes according to the chemical composition of their primary energetic ingredients. A single-base powder contains nitrocellulose, whereas a double-base powder contains nitrocellulose and nitroglycerine. The energetic ingredients in triple-base powders are nitrocellulose, nitroglycerine, and nitroguanidine, but because triple-base powders are primarily used in large caliber munitions, they are difficult to obtain on the open market.

Composition and Manufacturing

The major classes of compounds in smokeless propellants include energetics, stabilizers, plasticizers, flash suppressants, deterrents, opacifiers, and dyes (Bender 1998; Radford Army Ammunition Plant 1987).

Energetics facilitate the explosion. The base charge is nitrocellulose, a polymer that gives body to the powder and allows extrudability. The addition of nitroglycerine softens the propellant, raises the energy content, and reduces hygroscopicity. Adding nitroguanidine reduces flame temperature, embrittles the mixture at high concentration, and improves energy-flame temperature relationship.

Stabilizers prevent the nitrocellulose and nitroglycerine from decomposing by neutralizing nitric and nitrous acids that are produced during decomposition. If the acids are not neutralized, they can catalyze further decomposition. Some of the more common stabilizers used to extend the safe life of the energetics are diphenylamine, methyl centralite, and ethyl centralite.

Plasticizers reduce the need for volatile solvents necessary to colloid nitrocellulose, soften the propellant, and reduce hygroscopicity. Examples of plasticizers include nitroglycerine, dibutyl phthalate, dinitrotoluene, ethyl centralite, and triacetin.

Flash suppressants interrupt free-radical chain reaction in muzzle gases and work against secondary flash. They are typically alkali or alkaline earth salts that either are contained in the formulation of the propellant or exist as separate granules.

Deterrents coat the exterior of the propellant granules to reduce the initial burning rate on the surface as well as to reduce initial flame temperature and ignitability. The coating also broadens the pressure peak and increases efficiency. Deterrents may be a penetrating type such as Herkoteâ, dibutyl phthalate, dinitrotoluene, ethyl centralite, methyl centralite, or dioctyl phthalate; or an inhibitor type such as Vinsolâ resin.

Opacifiers enhance reproducibility primarily in large grains and keep radiant heat from penetrating the surface. They may also enhance the burning rate. The most common opacifier is carbon black.

Dyes are added mainly for identification purposes.

Other ingredients may be one of the following:
A graphite glaze used to coat the powder to improve flow and packing density as well as to reduce static sensitivity and increase conductivity
Bore erosion coatings applied as a glaze to reduce heat transfer to the barrel, but uncommon in small-arms propellants
Ignition aid coatings that are most commonly used in ball powders to improve surface oxygen balance

Figure 1 Common smokeless powder morphologies Click to enlarge image.
Chemical composition is one important
characteristic defining smokeless propellants; however, another important characteristic is its morphology. Shape and size have a profound effect on the burning rate and power generation of a
powder (Meyer 1987). Common particle shapes of smokeless propellants include balls, discs, perforated discs, tubes, perforated tubes, and aggregates (Bureau of Alcohol, Tobacco and Firearms 1994; Selavka et al. 1989). A few common types of smokeless powder morphologies can be seen in Figure 1 (Bender 1998).
Morphology also lends clues to whether a powder is single- or double-base (Bender 1998). Most tube and cylindrical powders are single-base, with the exception of the Hercules Reloaderâseries. Disc powders, ball powders, and aggregates are double-base, with the exceptions being the PB and SR series powders manufactured by IMR Powder Company of Plattsburg, New York.

Except for ball powder, smokeless powder is manufactured by one of two general methods, differing in whether organic solvents are used in the process (Meyer 1987; Radford Army Ammunition Plant 1987). A single-base powder typically incorporates the use of organic solvents. Nitrocellulose of high- and low-nitrogen content are combined with volatile organic solvents, desired additives are blended with them, and the resulting mixture is shaped by extrusion and cut into specified lengths. The granules are screened to ensure consistency, and the solvents are removed. Various coatings, such as deterrents and graphite, are applied to the surface of the granules. The powder is dried and screened again, then blended to achieve homogeneity.

The manufacture of double-base powders requires the addition of nitroglycerine to the nitrocellulose. Two methods can be used. One method uses organic solvents, the other uses water. The organic solvent method mixes nitrocellulose and nitroglycerine with solvents and any desired additives to form a doughy mixture (Meyer 1987; National Research Council 1998; Radford Army Ammunition Plant 1987). The mixture is then pressed into blocks that can be fed into the extrusion press and cutting machine. The resulting granules are screened prior to solvent removal and the application of various coatings. The powder is dried, screened again, then blended to achieve homogeneity. The water method adds the nitroglycerine to a nitrocellulose water suspension to form a paste (Meyer 1987; Radford Army Ammunition Plant 1987). The water is removed by evaporation on hot rollers, then the dried powder is shaped by extrusion and cutting.

Triple-base powders use a solvent-based process similar to the double-base powder process (Meyer 1987; Radford Army Ammunition Plant 1987). Nitrocellulose and nitroglycerine are premixed with additives prior to the addition of a nitroguanidine solvent mixture. The nitroguanidine is incorporated into the overall mass without dissolving in the other materials. The final mixture is then extruded, cut, and dried.

The manufacture of smokeless ball powder requires a more specialized procedure (National Research Council 1998). Nitrocellulose, stabilizers, and solvents are blended into a dough, then extruded through a pelletizing plate and formed into spheres. The solvent is removed from the granules, and nitroglycerine is impregnated into the granules. The spheres are then coated with deterrents and flattened with rollers. Finally, an additional coating with graphite and flash suppressants is applied, and the batch is mixed to ensure homogeneity.

In the manufacturing process, smokeless powders are recycled and reworked (National Research Council 1998). When a powder within a batch is found to be unsatisfactory, it is removed and returned to the process for use in another lot. Manufacturers save money by recycling returns by distributors or the return of surplus or obsolete military powders. Hence, reworking and recycling the material assures good quality control of the final product, reduces costs by reusing materials, and reduces pollution by avoiding destruction by burning.

Distribution

The production of smokeless powders is big business in the United States, where approximately 10 million pounds of commercial smokeless powders are produced each year. Most of the powder is sold to the original-equipment manufacturers to be used for manufacturing ammunition. A large amount is sold to domestic and foreign militaries (National Research Council 1998). The rest is sold in individual canisters (ranging from ½-pound cans to 12- or 20-pound kegs) to gun stores or hunting and shooting clubs for hunters and target shooters who prefer to hand load their own ammunition.

There are several ways smokeless powders are distributed within the United States (National Research Council 1998). Some manufacturers, foreign or domestic, produce, package, and sell their own powders commercially. They may also sell in bulk to resellers and to original-equipment manufacturers that repackage and sell it under their own labels. The powder manufacturers and repackagers may disburse large quantities of canister powders to distributors who later sell to smaller distributors and wholesalers, who in turn, supply cans to dealers, gun shops, shooting clubs, and other retailers. At this point, consumers can purchase a 1-pound canister of powder for approximately $15 to $20 from a retailer, though the cost per pound can be cheaper if bought by the keg or acquired through a gun club (National Research Council 1998).

Manufacturers who produce smokeless powders for the U.S. military can distribute it either by selling the powder directly to the military or by selling them the preloaded ammunition. Powders can also be shipped to U.S. military subcontractors, foreign governments, or foreign loading companies for loading into military ammunition (National Research Council 1998).

Improvised Explosive Devices

An explosion is the result of energy-releasing reactions, generally accompanied by the creation of heat and gases (a notable exception is thermites). A distinguishing characteristic of an explosion is the rate at which the reaction proceeds. There are low-order and high-order explosives, based on the speed at which the explosives decompose. In low-order explosives, the process of decomposition, called the speed of deflagration or burning, produces heat, light, and a subsonic pressure wave. (The reaction speed of the deflagrating material is less than the speed of sound.) In high-order explosives, decomposition occurs at the speed of detonation, creating a supersonic shock wave that causes a virtually instantaneous buildup of heat and gases. Table 1 shows some differences in low-order and high-order explosives (Bureau of Alcohol, Tobacco and Firearms 1994; National Research Council 1998; Saferstein 1998).

For low-order explosives, rapid deflagration causes the production of large volumes of expanding gases at the origin of the explosion. The heat energy from the explosion also causes the gases to expand. When the explosive charge is confined in a closed container, the sudden buildup of expanding pressure exerts high pressure on the container walls causing the container to stretch, balloon, then burst, releasing fragments of debris to nearby surroundings. It is this fragmented debris that produces the fatal result following the deflagration of an improvised explosive device (Saferstein 1998).

The safest and most powerful low-order explosive is smokeless powder. These powders decompose at rates up to 1,000 meters per second and produce a propelling action that makes them suitable for use in ammunition. However, the slower burning rate of smokeless powder should not be underestimated. The explosive power of smokeless powder is extremely dangerous when confined to a small container. In addition, certain smokeless powders with a high-nitroglycerine concentration can be induced to detonate. On the other hand, high-order explosives do not need containment to demonstrate their explosive effects (Saferstein 1998). These materials detonate at rates from 1,000 to 8,500 meters per second, producing a shock wave with an outward rush of gases at supersonic speeds. This effect proves to be more destructive than the fragmented debris.

The typical smokeless powder improvised explosive device, a pipe bomb, is roughly 10 inches long and 1 inch wide and contains approximately ½ pound of powder. The materials used for these devices are cheap and readily obtainable at commercial establishments. Smokeless powder is attractive for use in improvised explosive devices, because it is readily available and has the potential for a powerful explosion when the powder is placed in a closed container (National Research Council 1998). Larger explosive devices usually use bulk materials such as ammonium nitrate and fuel oil, typically purchased in greater quantity at an even cheaper price.

Many types of containers are used in the construction of smokeless powder bombs (National Research Council 1998). Whereas metal pipes are most common, plastic pipes, cans, CO2 cartridges, and glass or plastic bottles have been used. These containers are often placed within larger packages for ease of transport and concealment.


Figure 2 Pipe Bomb Click to enlarge image.
Another important part of the powder bomb is the initiation system, which provides the impetus to start the powder burning within its container (National Research Council 1998). A few examples include cigarettes, matches, and safety fuses (Scott 1994; Stoffel 1972). Improvised explosive devices utilizing smokeless powders within a robust container often include an initiation system, as shown in Figure 2 (Scott 1994).

Using data from the National Research Council on reported actual and attempted bombings using propellants during the five-year period from 1992-1996, Table 2 illustrates an average of 653 incidents per year involving the use of black and smokeless powders. Bombs containing black or smokeless powders were responsible for an average yearly count of about 10 deaths, 83 injuries, and almost $1 million in property damage for each of the five years. Using the National Research Council's data involving devices filled with black and smokeless powders, Table 3 illustrates the number of actual bombings that caused at least one death, one injury, or a minimum of $1,000 in property damage, as well as attempted bombings aimed at significant targets (National Research Council 1998).

Analysis


Figure 3 Gradient HPLC analysis of an IMR 700X smokeless powder. Conditions Restek C-8 Column, 36-80% methanol/water gradient, 1 ml/min, UV detection at 230 nm. Figure courtesy of Chad Wissinger, Ohio University Click to enlarge image.
Many methods for the analysis of smokeless powders have appeared over the years. These procedures have been extensively reviewed in a number of recent texts (Beveridge 1998; National Research Council 1998; Yinon and Zitrin 1993). The initial characterization of the powders is assessed using powder morphology and spot tests. Various instrumental analytical techniques allow organic additives such as nitroglycerine, diphenylamine,
ethyl centralite, dinitrotoluene, and various phthalates to be detected and quantitated. These materials are usually analyzed using gas chromatography-mass spectrometry (Martz and Lasswell 1983) and liquid chromatography (Bender 1983; McCord and Bender 1998). Figure 3 illustrates the analysis of an IMR 700X powder using gradient high performance liquid chromatography (Wissinger and McCord 2002). More recently, methods involving capillary electrophoresis have also been shown to be effective (Northrop et al. 1991; Smith et al. 1999). Fourier transform infrared microscopy can be used for the identification of nitrocellulose (Zitrin 1998).


Figure 4 IC Analysis of H414 smokeless powder by Hodgdon. Conditions Nucleosil Anion IIÒ Column, 1mM DCTA pH 5.2, 1.5 ml/min, UV detection at 205 nm. Click to enlarge image.
The process of manufacturing smokeless powders provides sources of inorganic ions that are present in postblast residue. These can be analyzed by ion chromatography. Although not unique to propellants, the presence of these ions can be used
in forensic analysis to aid in the identification of the unknown powder. Potassium sulfate, sodium sulfate, potassium nitrate, barium nitrate, and other salts
may be added during the processing of the powder. Nitrate, sulfate, hydrogen sulfide, chloride, and nitrite may appear as a result of the reactions for treating
the cellulose to obtain nitrocellulose (Radford Army Ammunition Plant 1987). Figure 4 illustrates the analysis of H414 smokeless powder using ion chromatography. Also documented has been the presence of various cations found in the residue of smokeless powders after deflagration (Hall and McCord 1993; Miyauchi et al. 1998).

Conclusions

The wide variety of chemical components and the different morphologies of smokeless powders present a challenge for the forensic investigator. Physical characteristics of partially burned and unburned powder as well as the organic and inorganic materials that remain must be considered in the analysis of postblast residue. Although there are many techniques available for the determination of components in smokeless powder residue, the various formulations of powders make it necessary to continue the advancement of existing analyses and to develop new methods for testing the full range of available smokeless powders.

References

Bender, E. C. Analysis of low explosives. In: Forensic Investigation of Explosives. A. Beveridge, ed. Taylor and Francis, London, 1998, pp. 343-388.

Bender, E. C. Analysis of smokeless powders using UV/TEA detection. In: Proceedings of the International Symposium on the Analysis and Detection of Explosives. U.S. Government Printing Office, Washington, DC, 1983, pp. 309-320.

Beveridge, A., ed. Forensic Investigation of Explosives. Taylor and Francis, London, 1998.

Bureau of Alcohol, Tobacco and Firearms, Arson and Explosives Incidents Report (1994). ATF P3320.4, Department of the Treasury, Washington, DC, 1994.

Hall, K. E. and McCord, B. R. The analysis of mono- and divalent cations present in explosive residues using ion chromatography with conductivity detection, Journal of Forensic Sciences (1993) 38:928-934.

Martz, R. M. and Lasswell, L. D. Identification of smokeless powders and their residues by capillary column gas chromatography/mass spectrometry. In: Proceedings of the International Symposium on the Analysis and Detection of Explosives. U.S. Government Printing Office, Washington, DC, 1983, pp. 245-254.

McCord, B. and Bender, E. C. Chromatography of explosives. In: Forensic Investigation of Explosives. A. Beveridge, ed. Taylor and Francis, London, 1998, pp. 231-265.

Meyer, R. Explosives. 3rd rev., Weinheim, New York, 1987.

Miyauchi, H., Kumihashi, M., and Shibayama, T. The contribution of trace elements from smokeless powder to post-firing residues, Journal of Forensic Sciences (1998) 43:90-96.

National Research Council, Committee on Smokeless and Black Powder. Black and Smokeless Powders: Technologies for Finding Bombs and the Bomb Makers. National Academy Press, Washington, DC, 1998.

Northrop, D. M., Martire, D. E., and MacCrehan, W. A. Separation and identification of organic gunshot and explosive constituents by micellar electrokinetic capillary electrophoresis, Analytical Chemistry (1991) 63: 1038-1042.

Radford Army Ammunition Plant. Processing Manual. Radford, Virginia, 1987.

Saferstein, R. Criminalistics: An Introduction to Forensic Science. 6th ed., Prentice Hall, Upper Saddle River, New Jersey, 1998.

Scott, L. Pipe and Fire Bomb Designs: A Guide for Police Bomb Technicians. Paladin Press, Boulder, Colorado, 1994.

Selavka, C. M., Strobel, R. A., and Tontarski, R. E. Systematic identification of smokeless powders, an update. In: Proceedings of the Third Symposium on the Analysis and Detection of Explosives. Berghausen, Fraunhofer Institute fur Chemische Technologie, 1989, Chapter 3, pp. 1-27.

Smith, K. D., McCord, B. R., MacCrehan, W. A., Mount, K., and Rowe, W. F. Detection of smokeless powder residue on pipe bombs by micellar electrokinetic chromatography, Journal of Forensic Sciences (1999) 44:789-794.

Stoffel, J. Explosives and Homemade Bombs. Charles C. Thomas, Springfield, Illinois, 1972.

Wissinger, C. and McCord, B. R. A reversed phase HPLC procedure for smokeless powder comparison, Journal of Forensic Sciences (2002) 47:168-174.

Yinon, J. and Zitrin, S. Modern Methods and Applications in Analysis of Explosives. John Wiley, Chichester, United Kingdom, 1993.

Zitrin, S. Analysis of explosives by infrared spectrometry and mass spectrometry. In: Forensic Investigation of Explosives. A. Beveridge, ed. Taylor and Francis, London, 1998, pp. 267-314.



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Forensic Science Communications April 2002— Volume 4— Number 2

quote:

Reply

rcaligula, perhaps the source of confusion is that my original question was a bit retorical in nature. The data shows consistently lower pressures for double-based powders when like velocities are compared (and, of course, when powders of reasonably equivalent quicknesses are used). The only people with their minds pre-"made up" are those who won't actually look at the data such as...

...vapohog who simply writes a pat "no" followed by insulting remarks.

243winxb, that's an interesting article but it doesn't address the question.

quote:

Originally posted by ramrod340:
...I have no further comment...

Good, you weren't addressing the data anyway.

quote:

rcaligula, perhaps the source of confusion is that my original question was a bit retorical in nature. The data shows consistently lower pressures for double-based powders when like velocities are compared (and, of course, when powders of reasonably equivalent quicknesses are used). The only people with their minds pre-"made up" are those who won't actually look at the data such as...

...vapohog who simply writes a pat "no" followed by insulting remarks.

243winxb, that's an interesting article but it doesn't address the question.

quote:

quote:
Originally posted by ramrod340:
...I have no further comment...

Good, you weren't addressing the data anyway.

You're doing a great job making friends!

I'm sure you'll get plenty of help here on the forums from everybody who has the knowledge to answer your questions!

Keep it up!

You should change your handle to "Wiseass"!!!!!

quote:

Originally posted by rcamuglia:
You're doing a great job making friends!

I'm sure you'll get plenty of help here on the forums from everybody who has the knowledge to answer your questions!

Keep it up!

You should change your handle to "Wiseass"!!!!!

Or something to that effect.... a horse's rear end comes to mind!

quote:

Originally posted by Wismon:
Do double-based powders operate at lower pressures than their single-based counterparts? Some of the data seems to suggest this. Any comments or explanations would be welcome. Thanks.

No, IMO. SAAMi sets the pressure/PSI maximum for each caliber/round. A double based powder has more energy/faster, because of the nitroglycerine added to it. This is my guess?? Another question you might ask is "What produces the lower heat/less throat erosion, single or double based powders?

quote:

it seems to me that double-based powders provide the same velocities as single-based powders of similar quicknesses, but do so at lower pressures.

This would seem to be true if not loading to maximum pressures. At a given velocity, the double base would peak pressure faster, with less volume of powder taking up space in the cartridge. Different case volumes between calibers act differently to the burning rate of A powders. I would worry more about the heat that is made by the same pressue loading, longer barrel/throat life with cooler temperatures.Total guess on my part, as i dont really have a clue.

quote:

Any comments or explanations would be welcome. Thanks.

Apparently not.

Gosh, I cannot believe hotcore has not chimed in with the answer. He claims to be an engineer with all sorts of gun pressure experience. He was the poster boy for strain gauges you know.

I believe Ramrod has it correct. This is not rocket science, basically the more energy you pack behind the bullet, the more energy available to be converted to kinetic energy (velocity). Double base powders have a bit more energy content than single base powders, and thus, given equal pressure (e.g., 65,000 PSI) one should get a bit more kinetic energy in the bullet. My assumption is that the added NG in double based powders increases the area under the pressure curve, relative to single based powder.

My experience would support this observation. IMR powders tend to be single based whereas Alliant (reloader series) and Norma powders are double based. I always get a bit more velocity from Alliant and Norma powders than IMR powders given equivalent pressure signs.

Regards, AIU

rcaligula, you mean you’re not my friend? Aw, shucks. Does that mean I won’t get an evite to your slumber party?

vapohog, it sounds like you have a specific interest in horses’ rear ends.

onfonzie, I asked for comments or explanations; not out-of-hand dismissals, opinions based off of the ignoring of data, and unprovoked insults of my inquiry.

243winxb and Ackley Improved User, thank you for your well-thought-out responses. Upon further reflection it seems to me to be incontrovertible: if double-based powders add nitroglycerine for increased energy then the only way that extra energy can be tapped is if it doesn’t exceed allowable pressures. If it does so by elongating the pressure curve then all the better but the point is that it can’t exceed the max pressure. So…for the same max pressure you get additional velocity or…if you hold velocity constant you would have to have lower pressure. Wouldn’t that be the case? For a given powder it doesn’t seem likely that you could just shorten the pressure curve without also lowering it.

quote:

Ignored post by Wismon posted 27 January 2011 02:47

when you're not worth reading!

vapolog, if you're making a public response to my post declaring that you're ignoring me then you're not ignoring me, ignore-amous.

It’s interesting how your thread just fell apart Wismon. Maybe you shouldn’t ask rhetorical questions (a question asked for the sake of persuasive effect rather than as a genuine request for information).

quote:

Sure. Pull up virtually any one of the examples posted on this page and compare them on a velocity-by-velocity basis. In other words, it appears that for a given velocty the double-based powders come in at a lower pressure. Compare, for example, 180 gr bullets using 4831 vs RL22.

You seem to have missed the point of the information you are looking at. The velocity:speed differences you see are due how different burn rates may or may not match the cartridge and bullet, not the composition of the powder as such.

Double base powders tend to burn a bit hotter than single based and can damage a bore faster, plus they tend to pack more energy in a grain, but 60 K PSI is 60 K PSI no matter what powder is used to get there.

Jim C, the final velocity of the bullet is directly proportional to the total area under the pressure curve. Thus, not all 60,000 peak PSIs are the same - a more sustained average high pressure produced by relatively more slow-burning powder will produce more velocity than less fast burning powder that peaks more quickly and fades faster. This principle is easily and clearly demonstrating by the Quick Load internal ballistics program. Regards, AIU

quote:

Originally posted by MickinColo:
It’s interesting how your thread just fell apart Wismon. Maybe you shouldn’t ask rhetorical questions (a question asked for the sake of persuasive effect rather than as a genuine request for information).

MickinColon,

It's "interesting" how your sanctimony falls apart. Perhaps you shouldn't make rhetorical statements (a statment made as an underhanded swipe at someone rather than as a genuine suggestion).

Jim C.,

Expounding on what Ackley Improved User wrote: you can't have "more energy" at the "same pressure" without an increase in velocity. Therefore if you hold the velocity constant either the pressure or the energy goes down. I fail to see how you can reduce a few grains of powder to drop the velocity and hold it constant with that of an equivalent single-based powder and not have a comensurate drop in pressure.

quote:

Originally posted by Wismon:
Jim C.,

Expounding on what Ackley Improved User wrote: you can't have "more energy" at the "same pressure" without an increase in velocity. Therefore if you hold the velocity constant either the pressure or the energy goes down. I fail to see how you can reduce a few grains of powder to drop the velocity and hold it constant with that of an equivalent single-based powder and not have a comensurate drop in pressure.

This is the kind of post one gets when he types more than he reads! Wismon isn't capable of understanding other than simple relationships! I wonder about those as well!

I might venture to guess that wismon is Busheler or his relative.

quote:

Originally posted by rcamuglia:
I might venture to guess that wismon is Busheler or his relative.