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The scoop on pressures with double the powder

Discussion in 'Shooting Related Threads' started by joe kuhn, Sep 30, 2009.

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  1. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    I asked Tom Armbrust, who tests shotshell speed and pressure as a business, the following:

    "Have you ever tested double charges of powder? I'm curious what pressures you would get on a double charge of Red Dot, for example, with 1-1/8 oz of shot."

    And received this response:

    "Yes I have, using a fast burn rate powder like 700-X with an
    1-1/8 oz of shot pressures run in the 34,000 PSI range. If you increase the shotcharge, the pressure goes out of sight. An industry 12 GA proof load run 19,000 PSI."

    Sounds to me like our proofing process is faulty! If we proove a gun is safe with 19,000 psi and a reloader in shooter X's basement can error and give it 34,000 psi, we are setting ourselves up for failure.

    I've followed up with Tom:

    "How can we have confidence in the proofing process of gun barrels, if a reloader in shooter X's basement can go way beyond proof load pressures?"

    We'll see what he says. Stay tuned.
     
  2. Carol Lister

    Carol Lister TS Member

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    The above exchange is the reason why gun manufacturers specifically warn against using anything but factory loads in their guns.

    <blockquote>"Sounds to me like our proofing process is faulty! If we proove a gun is safe with 19,000 psi and a reloader in shooter X's basement can error and give it 34,000 psi, we are setting ourselves up for failure."</blockquote>

    It's this logic that's faulty. This statement should more properly read...

    <blockquote>"Sound to me like people who reload should learn to pay attention to what they're doing. If we PROVE a chamber can withstand 19,000 PSI and shooter X can error in his basement and give it 34,000 PSI, then maybe shooter X shouldn't be reloading."</blockquote>

    It will be easy to construct barrels that can withstand whatever mistakes the people who reload their own ammo can make; the difficulty will be finding shooters who can lift the guns!

    Carol Lister
     
  3. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    I disagree. Guns should handle common mistakes shooters/reloaders make. How do you know there aren't guns out there already that can handle double the powder charge? You don't because the testing procedure doesn't exist.

    Guns should also be able to handle a wad stuck in a barrel and a base wad from a AA stuck in a barrel as well. Do we know what pressures those problems lead to? Probably not.

    We have a lack of information that can allow weak mfr processes to build guns that blow up. That's where our correction should lie. Try to take somebody's reloader away from them. I see no prctical solution to your line of thinking.
     
  4. ivanhoe

    ivanhoe Well-Known Member

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    joe kuhn

    "Guns should also be able to handle a wad stuck in a barrel and a base wad from a AA stuck in a barrel as well. Do we know what pressures those problems lead to?"

    Just out of curiosity why do you think that 20GA ammo is yellow instead of red or green or blue or maroon? It because of barrel obstructions. They have been trying for years to figure a way to stop the effects of blocked barrels.

    Along come Joe and he is going to revolutionize the design of the modern shotgun when he is done the shotgun will be like the tank virtually indestructible. Its just to bad Joe that there are so many people in the world that don't realize you just can't fix stupid.

    BTW they have been trying for years and years to build a better mouse trap. Well guess what they evidently haven't made it yet because they keep coming up with new designs all the time. They are new but none is any better.

    Bob Lawless
     
  5. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    So either Tom's data or equipment is at fault or Bruce Bowen's destructive testings are flawed. Bruce said he never seen pressures much over 20,000 range from double charges, now Tom claims the 2X charge is 34,000 PSI.
     
  6. jimrich60

    jimrich60 Member

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    Following joe's logic, we need to build cars that cannot go faster than 5mph, and have total driver enclosures so that drivers can't get hurt by their own stupid driving mistakes. Since you can get burned by hot coffee, makers should only serve coffee cold. We also should ban electricity because misuse of it can cause harm. The list would be endless. Wonder what joe's "stupid proof" world will look like? I think I will stay in the one we have, where the individual is responsible for his/her own actions, and "stupid" has consequences.

    Jim R
     
  7. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    Carol,

    There's a neat post on another thread where a guy says you can design barrels in a computer CAD program, specifying steel, thicknesses, etc. and see what pressures it will take. Intrigueing, eh?

    Bruce - are you out there?
     
  8. Hauxfan

    Hauxfan Well-Known Member

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    Maybe we all need to shoot 30 pound 12 gauge shotguns.............NOT!

    Hauxfan!
     
  9. sliverbulletexpress

    sliverbulletexpress TS Member

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    Joe this is not a personal attack but somebody has to say this. Some newer readers who have not followed your exploits in firearm design may think you know more than you do. Your posts lately seem to have an agenda..anti gun company except for Bowen or DeVault and such. Very transparent.

    The thing is that you may be a great computer nurd but you have no to very little apparent knowledge of firearms. Neither common sense wise or from education. Just how long have you been around firearms, how many rounds have you actually fired, how many rounds have you reloaded, how many different guns have you owned, how long have you been trap shooting? You are addressing a helluva a lot of experience on this forum with your crap.

    What you are doing is stirring the pot with a poor argument, a nutty argument. No one in their right mind would design a gun that couldn't be blown up and expect it to sell. It would would be very heavy and very expensive, a worthless goal.

    Most of us on here have loaded and shot 100's of thousands if not millions of reloads with no real problems with our ammo or guns, ever.

    Why don't you try and re-invent Windows, something more in your field and possibly achievable. I want a system that will never crash, never slow down at all ever, never glitch, never quit, not even if I load the newest worst virus imaginable in it, even if I make my own software. Let me know when you have it.

    With all due respect. SBE
     
  10. Alno

    Alno TS Member

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    "There's a neat post on another thread where a guy says you can design barrels in a computer CAD program, specifying steel, thicknesses, etc. and see what pressures it will take."

    Just like the computer weather modeling?
     
  11. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Advanced technology aside for a moment, how did the Winchester mod. 21 shoot proof loads all day without any bad effects on that gun?

    On another thread someone stated a test on an Zoli shotgun surpassing centerfire rifle chamber pressures? What's up with that? Hap
     
  12. rhymeswithorange

    rhymeswithorange Member

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    question for Joe, how would your Mach One handle 34k psi? Are you confident that it wouldn't blow apart? If you are not absolutely confident that it can handle it, then by your logic, you shouldn't be shooting it.

    Will all respect due.

    Dave
     
  13. 221

    221 Banned User Banned TS Supporters

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    I can't imagine someone that works in the software industry making a joke of Stress Analysis software.......Shows their true colors
     
  14. tom berry

    tom berry Active Member

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    I'd like to know how he got a double charge of 700X in a casing with a full 1 1/8 oz of shot on top of it.

    I thought I had a double charge of powder one time so I tried to duplicate it. The shot cup was to the top of the hull and I had shot everywhere.

    I guess I could have finished it off with in the crimping stations and it might have closed enough to keep the shot in the case. But I'm sure it would have been very noticable that something wasn't right with that shell.

    Anybody that stupid deserves to have their gun blown up. Just hope they don't take someone else with them.
     
  15. BBowen

    BBowen Member

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    i can only repeat what we found on our reloads. we shot double charges of red dot with 2 1/4 oz of shot and NO WAD and recorded pressures within proof load ranges. we shot 20 rounds of this recipe and found very repeatable results. two charges of red dot with 1 1/8 oz of shot (with a wad that would work) also produced pressures within the proof load range.

    also, i should point out that two ballisticians that i have talked to confirmed that it is unlikely that those recipes will produce pressures outside the proof load range. they also told me that it would probably require a very heavy projectile (like a 1 or 2 pound rod) loaded into the shotshell to reliably cause catastrophic failures in a shotgun.

    again, i am not recommending that anyone try what we did here under very controlled conditions. it is dangerous business and everyone should be cautious and safe.

    bruce bowen www.bbguns.net
     
  16. 870

    870 Well-Known Member

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    Tim:

    I wasn't there but I think it's obvious they couldn't get a double powder charge AND 2 1/4 oz. of shot in a hull if they used a wad. They were trying all sorts of combos to blow that thing and this was just one of them.

    Note that he said they DID use a wad w/ the double powder charge and 1 1/8 of shot w/o exceeding the proof load range.
     
  17. pyrdek

    pyrdek Well-Known Member

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    Almost every posting regarding double powder charges uses a very fast burning powder as the double charge powder.

    I was just wondering what might happen if a slow burning powder was doubled charged. Yes, I realize that in typical use a fast burning powder generates higher INSTANTANEOUS pressure but how about a slower burning powder having time for the pressure to build after the wad clears the forcing cone but not the muzzle. Most barrels seem to be thinner once you get past the receiver portion and into the forearm portion. Could not a longer sustained pressure curve, that is significantly higher than the normal single charge curve but still not as high as the instantaneous pressure from a fast burning powder closer to the receiver, put a lot of stress on a weaker part of the barrel?

    Granted the heavier weight charge normally used in slower burning powder would seem to occupy more space in the shell but with a wad that is crushed, it might still be possible to fit it in and get enough crimp to close the shell. As a follow-up, how about a double charge of slower powder but with a slightly lesser shot weight. Could the extra barrel space, because of the wad/shot being up the barrel an inch or two farther, contribute to a detonation effect if slower powder were used?
     
  18. BBowen

    BBowen Member

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    two charges of red dot and 2 1/4 oz of shot gave the highest pressures that we recorded. the reason i was so interested in this recipe is that it is the one that always comes up when i was inquiring about a reason for catastrophic shotgun failures. an ammunition development engineer told me on several occasions that this was the load to do the job. i have always felt that the liklihood of someone making such a reload without being aware of doing so is nil but possible of course. even making a reload with two charges of powder and one charge of shot is unlikely because the reloader would have to (for that shell only) pick up a suitable wad or shot would be running out of the shell.

    i just don't think that pressure is the issue in most catastrophic failures. if there is a high velocity gas leak--a failure can occur. a case separation in a rifle and the oftentime catastrophic results is the best illustration and easily reproduced by pushing the shoulder back and creating too much headspace. i think POSSIBLY a failure in a shotgun could be repoduced by making a very small orifice in the chamber wall especially if there was an unsupported area between the barrel extension and the monobloc hole.

    bruce bowen www.bbguns.net
     
  19. Chichay

    Chichay TS Supporters TS Supporters

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    Trying to foolproof a gun is a fool's task and a litigator's dream. And they are not mutually exclusive.
     
  20. Ahab

    Ahab Well-Known Member

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    Any time that you make something fool proof....along will come a bigger fool!
     
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