BP VS smokeless pressure curve and effects on guns?

Discussion in 'Blackpowder' started by gilgsn, Dec 8, 2017.

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  1. J-Bar

    J-Bar Member

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    On the contrary, I think the chart supports it. It is not how fast the pressure peaks, it is how high the pressure goes. Black powder gives a gentler longer lasting push; smokeless gives a hard sharp kick in butt! Or, if you wish, a man can push a car and start it to roll, but if he runs at it as fast as he can and crashes into it, the car isn’t going to move (and the runner gets hurt in the process). Experience bears out the analogy. It is smokeless powder that blows guns up, not black powder.
     
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  2. rdstrain49

    rdstrain49 Member

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    J-Bar, absolutely correct. Seems some folks choose to not understand, to what purpose I can not imagine
     
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  3. Gaucho Gringo

    Gaucho Gringo Member

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    Plus the conversion cylinders are made out of better steel to take the smokeless pressure of a cartridge loaded with smokeless powder. The greatest stress is in the chamber of a revolver.
     
  4. whughett

    whughett Member

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    Of course its higher, nitro powders have a hell of lot more energy grain for grain then black powder, and that energy is 100% utilized in a controlled burn. Black is one sudden boom with 40% to 50% or more blown out the end of the barrel. Its the pressure generated that blows the gun, and as you can also see from the chart the pressure drop occurred at the same point in time, and in that particular case occurred when the shot left the barrel, so don't see the "longer lasting push" mentioned. I'm just reading the chart not reading into it.

    I'm not saying or advocating using or experimenting with loose smokeless powder in firearms not designed to handle the higher pressures
     
    Last edited: Dec 10, 2017
  5. Driftwood Johnson

    Driftwood Johnson Member

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    Howdy

    I got that graph from a ballistics technician years ago. I have posted it on several gun boards over the years.

    I have posted it again here.

    pressure_curve.jpg



    The graph represents the pressure curves of two charges of powder used in a 12 gauge shotgun to accelerate 1 1/8 ounces of shot to 1200 fps. Notice it specifies this is a 3 Dram Equivalent load, which is what 82 grains of Black Powder would be.

    The problem with this chart is it does not specify exactly what Smokeless powder was used.

    But we can still generalize a few things from the chart. Being a shotgun load, the Smokeless powder is going to be a fairly fast powder.

    The important thing to notice in this chart is how much less pressure was developed with the Black Powder charge AND how much more spread out the curve is in duration.

    Notice the Smokeless curve is a sharp spike, peaking and declining much more quickly than the Black Powder charge. That is the key. The older steel (and iron) in Black Powder era guns was not able to take the sharp spike in pressure as well as modern steel can. Even if the over all Smokeless pressure had been less, the spike would still have been very narrow. This tends to impart a 'shock' to the metal, that older steel might now be able to absorb without shattering.

    Think of attaching a rope to your car to pull another car. If you accelerate very slowly and gradually, chances are the rope will not break and you will get the other car moving. On the other hand, if you start with a jerk, the rope may not be able to withstand the sudden increase in force, and may snap. Not a perfect analogy, but you get the idea.

    The older steel or iron of a Black Powder era gun may not be able to take the sudden shock of the sharp pressure spike.

    I argue about this with a guy on the S&W forum all the time, and it is indeed possible to formulate Smokeless charges with certain slow burning powders that will have a gentler curve and probably will not hurt the older steel. But those powders are not ones that are generally used with revolver cartridges. This guy has submitted formulas that he thinks are safe in the old guns, but I do not have pressure equipment to test them, and frankly, I don't want to risk my antiques on his say so, so I only shoot my old, 19th Century revolvers with Black Powder.

    Rifles are a different story. The cross section of the chamber wall of a rifle is much thicker than the thinnest cross section of a revolver cylinder. As I have said many times, it is the cylinder of a revolver that must withstand the pressure generated when a cartridge fires. Not the barrel, and not the frame. When a revolver blows up, it is almost always the cylinder that bursts, not the barrel. The cross section of the chamber wall of a rifle is thicker than the weakest point on a revolver cylinder. I have several 19th Century Winchesters, and although I only shoot them with Black Powder now, I would not hesitate to shoot most of them with mild Smokeless loads if I wanted to. The 1892 Winchesters anyway. They have a very strong action. I would not want to be firing Smokeless ammo in my 1873 rifles with their weaker toggle link lock up.

    Colt did not factory warranty the Single Action Army for Smokeless powder until 1900. Any Colt made before 1900 should not be fired with Smokeless powder. However, that is not to say that the first time an old gun is fired with Smokeless powder it is going to blow up. Obviously many old guns were fired with Smokeless powder over the years, and they have not blown up. Still, I stick to the rule and will not fire Smokeless in any of my old guns.

    Around 1901 Colt began marking the trigger guards their revolvers with a VP in an inverted triangle. VP stands for Verified Proof and its Colt's way of saying the gun has been proofed for Smokeless powder. This Bisley Colt was made in 1908.

    Verified%20Proof%20marking_zps4o8z0z3s.jpg




    Smith and Wesson is a bit harder to pin down. Several of their very early 20th Century catalogs warn against using Smokeless powder. They hedge their bets a little bit by claiming they cannot guarantee the reloader will exercise the proper care in reloading with the 'new' Smokeless powders. After a while S&W relented, but I can't give you an exact date.



    Iver Johnson completely redesigned their line of revolvers at the turn of the Century, using better steel, for Smokeless powder. They also completely redesigned the mechanism, and it is easy to tell a Black Powder era IJ from a Smokeless one.

    This is a Smokeless powder Iver Johnson. Notice the little owl on the grips faces backwards. Notice the shape of the cylinder locking slots, how they have a straight edge on both sides, meaning the bolt completely locks the cylinder in battery. Lastly, if the grips are removed, the hammer spring will be a coil spring.

    IverJohnsonHammerless01.jpg




    This is a Black Powder era Iver Johnson. Notice the little owl faces forward. Notice the shape of the cylinder locking slots. Only one straight edge, the hand prevents the cylinder from rolling backwards. And if the grips are removed, the hammer spring is a leaf spring.

    2834897460102804856S600x600Q85.jpg




    You will often hear that modern ammunition companies purposely load some of the old cartridges, such as 32 S&W or 38 S&W to low pressures because there are so many old guns out there. I am skeptical of this because as I stated earlier it is not just the amplitude of the pressure curve that matters, it is the the length of time that matters too. I have lots of old revolvers that chamber 32 S&W and 38 S&W. I do not trust modern ammunition companies to have a gentle enough pressure curve to fire in my antiques. My rule of thumb is the same as the Colt rule of thumb. I doubt if S&W had access to any better steels than Colt did at the end of the 19th Century. My 19th Century Smiths only get shot with Black Powder.

    Others can do as they choose.

    I believe somebody mentioned Trail Boss. Trail Boss is absolutely not a Black Powder substitute. It is a modern Smokeless powder with a very fast pressure curve. It is unsuited for use in 19th Century revolvers. Trail Boss was developed for Cowboy Action Shooting because many shooters load the old, large capacity cartridges such as 45 Colt way down to recoil like a light 38 Special. Put a small charge of Unique or any other common pistol powder in a big case like the 45 Colt or 44-40 and you run the risk of poor ignition and spotty performance because there is so much empty air space in the cartridge. That is why Trailboss was developed, the big, fluffy donut shaped grains take up a lot of space in the big old cartridges, leaving less empty airspace, resulting in more a consistent powder burn. But Trailboss is much too fast a powder to be considered a Black Powder Substitute.

    While I am on the soapbox, somebody mentioned the old thing about how slowly a trail of Black Powder burns. Not a good analogy to what it does in a cartridge. When you pour out a trail of Black Powder, like they did in the old Western movies, the flame has to jump across the airspace separating each of the powder grains. Not at all analogous to how it burns packed into a cartridge.

    P.S. If you look at the front of each of those pressure curves, you will see a little bump. More of a little spike with the Smokeless curve. Those are the little pressure spikes created as the primers ignite.
     
    Last edited: Dec 10, 2017
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  6. whughett

    whughett Member

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    Thank you Driftwood. Informative blog, and well written as usual. The note on the small pressure spikes caused by the primer would reinforce the reason I gave up on trying to load a 200 grain SWC designed for a 45ACP, no crimp groove, loaded in a 45C cartridge. That spike had started moving the bullet out of the case. A taper crimp just didn't do it. Same bullet in same case over 3f powder is a star performer.
     
    Last edited: Dec 10, 2017
  7. 4v50 Gary

    4v50 Gary Moderator Staff Member

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    The science is settled. Smokeless generates higher pressure faster and should not be used in black powder firearms.
     
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  8. Slamfire

    Slamfire Member

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    I don't know what good that would do, anyone who is delusional enough to shoot smokeless in Damascus twist barrels, I don't want to be near:might get hit by the shrapnel. Lots of confident idiots fly into the mountain side, just because they do it, does not mean I have to.

    A current custom blackpowder maker, it think it was Whittaker, I was CC on a email to him. The email asked him what steel he used for his barrels. I remember looking up the properties and the stuff was only a little better than wrought iron. You can use very weak materials, brass for example, with black powder. You can't with smokeless.

    In the early days of smokeless, the Germans had quite a big scandal with their M1888's. Metallurgy was rudimentary in the 1890's and Ludwig Loewe manufactured M1888's were blowing up. It was the technology of the era. It became a greater scandal because Ludwig Loewe was Jewish, and the German Anti Semites published tracts and newspaper articles claiming that "the Jews" were deliberately building defective rifles to hurt Christians. It was of course, rubbish. Smokeless was a new technology, so were smokeless rifles.

    Damascus barrels look beautiful but I would not trust one. Anyone making a barrel by winding a bundle of twisted steel/iron around a mandrel is going to overheat it at times and create a few bad welds.
     
  9. gilgsn

    gilgsn Member

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    I understand it, it's not what I'm asking about.

    Thanks everyone for your input, especially Driftwood Johnson.

    Of course, a similar charge of smokeless will produce more pressure than BP. What I wondered is, AT EQUAL PRESSURE, is smokeless more likely to damage an old gun and why? If the pressure spike is much faster in a smokeless cartridge, I understand. It's easy to confuse pressure and burn rate, and it gets rather confusing when there is conflicting information floating around. Now, let me know guys if I got this right:

    While black powder's burn rate is generally faster than smokeless, its pressure spike is not as sharp in a cartridge. While this is the closest to an answer I can come up with, I still wonder why a slower burning powder would produce more pressure; a matter of energy stored perhaps...

    I'll go further into detail with an example if this isn't clear enough...

    Say you have a test barrel with a pressure sensor, load a 45 Colt cartridge full of BP and shoot it... Let's say you get 15Kpsi, just for argument's sake. Now you choose a smokeless powder, say 2400, again, for argument's sake, and find a dose that gives you the same 15Kpsi, or whatever you measured in the BP cartridge... Now you have a BP and smokeless load that produces the same pressure, only with different powders and a different charge... Is the smokeless cartridge more likely to damage an old gun and why?

    Gil.
     
  10. J-Bar

    J-Bar Member

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    I will not speculate on a question that can be answered experimentally.

    Your variables are brand, model and age of gun

    Caliber

    Projectile weight

    Powder type

    Powder charge

    You will have to replicate each combination several times to be statistically significant.

    Let us know when you have completed your experiments. I look forward to reading your results.

    Not trying to be snotty, just saying that without specific details on each of the factors above, and actually trying the combination at the range, it is impossible to tell whether a gun will survive or not.

    Your question is like asking if sometimes it is ok for a kid to accept candy from a stranger. It probably is ok at times, but I am not going to encourage my kids to try it just for the sake of finding an exception to a generally accepted safe practice.

    Ruger proof tested their Old Army percussion revolver with Bullseye powder, and it survived. But nobody would ever say Bullseye can be used in the ROA.
     
    Last edited: Dec 11, 2017
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  11. Driftwood Johnson

    Driftwood Johnson Member

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    I have already answered your question.

    What he has done is select some powders that will duplicate both the height and length of a black Powder pressure curve. Then the pressure will not exceed the pressure generally achieved by Black Powder, AND the curve will be generally the same as far as not having a sharp pressure spike.

    No, I do not know what powders he uses. If you want to know that you will have to sign onto the Smith and Wesson forum and post the question, probably in the Antiques section under the Revolvers heading.

    In fact, I cannot even tell you how much pressure a full charge of Black Powder reaches in a cartridge such as 45 Colt or 44-40, even though I load them all the time. I just don't know. I suppose I could find out, but I really do not know how many PSI, or Crusher units are generated by such a charge.

    It is often said that you cannot stuff enough Black Powder into a modern replica Cap & Ball revolver to blow it up. I'm talking about one made with modern steel, not an antique. Black Powder, pound for pound, has much less explosive energy than most modern Smokeless powders. That is why the old cartridges such as 45 Colt and 44-40 were so big. To stuff in enough powder to guarantee putting a man down. That is why the case for 45 ACP is so much smaller. Developed as a Smokeless cartridge, it did not need as much case volume to reliably put a man down. If you want to blow up a modern made Cap & Ball revolver with Black Powder, you can't stuff enough powder into the chambers to do it. At least that is what is often said. Let's not forget the fact that the original Walker Colt, which had a powder capacity of something on the order of 70 grains per chamber, in fact did sometimes blow up. The statement to that effect in the movie The Unforgiven, made by the Gene Hackman character is true. The iron cylinders of the Walker would sometimes let go with a full charge of powder.

    But I digress. If you can select a Smokeless powder that will duplicate the pressure curve generated by Black Powder, in amplitude AND duration, you can probably safely fire that powder in an antique. Provided the antique is in good condition, and the steel or iron has not been over stressed over the years and ready to let go if pressures get a little bit too much.

    I do not have pressure testing equipment, nor the desire to develop such a load, I will simply continue to only fire Black Powder in my antique revolvers.

    Like this one:

    New%20Model%20Number%20Three%20Blue%2031022%2001_zpsmbzqn4z8.jpg
     
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  12. gilgsn

    gilgsn Member

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    Thanks again. I don't plan on ever using smokeless in a black powder gun, not even develop an equivalent load. I don't mind the cleaning up and BP is available here, so I have no reason to do it. I was just curious as to why for the same pressure, smokeless would be more dangerous, and a quick pressure spike does explain it. I have not reloaded BP cartridges yet, plenty of smokeless ones, but I have used lots of cap & ball replicas and still own a Pietta Remington 1858, using 35gr with a round ball, which has plenty of oomph! If all goes well I should be reloading .38-40 soon... That S&W looks great!

    Gil.
     
  13. Crawdad1

    Crawdad1 Member

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    Gil,
    How much power do you need?

    .44 Remington, 45 grain 3F Pyrodex 190 grain conical 1,023 ft/s 441 ft-lbs
    .44 Remington, 50 grain 3F Pyrodex 143 grain, .457 ball 1,207 ft/s 462 ft-lbs


    45 ACP +P 230 grain bullet 950 ft/s 461 ft-lbs
    45 ACP +P 230 grain bullet 950 ft/s 461 ft-lbs
    45 ACP 230 grain bullet 890 ft/s 404 ft-lbs
    45 ACP 160 grain bullet 1,050 ft/s 392 ft-lbs

    Never heard anyone say a 45 ACP is underpowered.
     
  14. gilgsn

    gilgsn Member

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    I don't know how you can fit that in a Remmy, though I've never tried... Lots of compression I guess. I've tried 35gr of 777 and that was enough for anything I'd want it to do! 777 is not available here in France unfortunately BTW, but we have Swiss BP.

    Gil.
     
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  15. Crawdad1

    Crawdad1 Member

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    We ain't done yet,

    44 Remington, 8 inch barrel, 40 grain Triple Seven, 140 grain, .454 ball 1229 ft/s @ 470 ft-lbs

    Swiss powders were not tested but compare favorably with Trip 7. You can get serious power out of those revolvers JUST using black powder. Would I use these loads on a regular basis? No I wouldn't but it is available.

    The Colt Walker and Dragoons can produce even more power using regular old black powder. (Pyrodex was used in the testing compares favorably to GOEx black powder)
     
    Last edited: Dec 12, 2017
  16. gilgsn

    gilgsn Member

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    Nice numbers, I'll have to give it a shot...
    Gil.
     
  17. Crawdad1

    Crawdad1 Member

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    If you want bigger numbers go to the Dragoon or Walker. :)
     
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  18. CraigC
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    CraigC Sixgun Nut

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    Even though some damascus guns were proved for nitro?
     
  19. Mizar

    Mizar Member

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    If I remember correctly, those were actually fake damascus barrels - solid steel barrel liner wrapped with a thin layer of damascus.
     
  20. CraigC
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    CraigC Sixgun Nut

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    I don't think The Double Gun Journal staff would be duped by fake damascus. Not to mention the destructive tests where the damascus barrels took more pressure than comparable fluid steel.
     
  21. Crawdad1

    Crawdad1 Member

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    Nope, they were Damascus barrels through and through.
     
  22. Mizar

    Mizar Member

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    Like I said: "If I remember correctly" - it was a long time ago when I read that somewhere. Furthermore, there are different types of damascus barrels, we can't just say "it's damascus!" and be done with it. 1900's nitro proof was much different than today - shorter chambers, lower pressures. BTW, I did found an interesting info regarding the Double Gun Journal article you were referring to:
    "John Brindle wrote about this in his excellent five part article in the Double Gun Journal , volume 4 issues 2 & 3, summer & fall 1993 , and volume 5 issues 1, 2 & 3. spring, summer and autumn 1994, in an article entitled BLACK AND NITRO, DAMASCUS & STEEL. In this series he cites the tests conducted by the Birmingham Proof House in 1888. Thirty nine different types of barrels, three examples for each type, were tested with increasing loads until a bulge of 0.01 inch or a burst occurred. The top four strongest barrels were, 1. English machine forged laminated steel, in three rods [a composition barrel], 2. English fluid compressed steel, Whitworth process [a fluid steel barrel], 3. English machine forged Best Damascus in 2 rods [a composition barrel], 4. English steel Siemens - Martin process [a fluid steel barrel]." The source: https://www.doublegunshop.com/gunther1.htm

    #1. A test conducted in the late 19 century.
    #2. Top strongest barrel - laminated steel, Nr. 2 - fluid steel, Nr. 3 - forged damascus.
     
  23. Slamfire

    Slamfire Member

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    It has been a while since I read about damascus barrels, it was in a Gun Digest. Maybe some passed a nitro proof. A proof is simply a 30% over test, it is not an endurance test. You know, there is an documented low number M1903 that passed the SA proof test, even though the receiver had not been heat treated. It did blow up in service. Mechanical items don't get better with use, they get worse.

    The NRA has an excellent article on these barrels:
    Gun Safety: Damascus-Barreled Shotguns
    https://www.nrafamily.org/articles/2016/11/14/gun-safety-damascus-barreled-shotguns/

    When damascus barrels were made, there where different attitudes about safety. A good example is safety in the workplace. Employers created dangerous, if not lethal workplaces, and employees accepted the fact they might come home in a box. In a program about the Titanic, the ship builder Harland and Wolff, the fatality rate was one death per 10,000 tons of ship. That was about one man dying per ship. Most due to falls or things falling on workers.

    I have only one life, I screw it up, I don't get rewarded with another, or even, a better one. One is all you get.
     
  24. rdstrain49

    rdstrain49 Member

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    Gil, if you are looking for a BP load that will rock your world, a full load of Swiss 3f behind a 250 grain flat nose in a 45 Colt will do the job. As I understand, that was approx. the original military load, which was subsequently changed to 2f BP to make the recoil more manageable for the average Trooper.
     
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  25. Driftwood Johnson

    Driftwood Johnson Member

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    I too have read articles about proofing Damascus barrels. When first made, most were just as strong as the early fluid steel barrels. The problem with a Damascus barrel is that over time corrosion can set in along the many feet of welds. The only way to know if a Damascus barrel is safe is to proof it again. If it does not blow up, it is safe.

    Coincidentally I have a friend who collects old shotguns. He has a couple of Damascus barrel guns, and he regularly shoots them with light smokeless loads. Not sure I would do the same, but he does. And he knows more about old shotguns than I do.
     
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