Quantcast
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

When Did 357 SAAMI Pressure Change?

Discussion in 'Handguns: Revolvers' started by Jaywalker, Dec 24, 2012.

Thread Status:
Not open for further replies.
  1. murf

    murf Member

    Joined:
    Nov 16, 2010
    Messages:
    3,073
    Location:
    arizona
    jaywalker,

    go to "sammi.org" under "info and specs" you will find the ansi standards that came out in 1993. their charts show both copper crusher and piezo electric transducer pressure data for the same test ammo. so, you can compare the two.

    fyi, i think there are 11 kinds of people: those who understand internal ballistics, those who don't, and those who have never been exposed (ignorant).

    murf
     
  2. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    Thanks, murf, it was there and I just didn't see it CUP and PSI compared. You wouldn't happen to have the pre-1993 standards, too, would you?
     
  3. murf

    murf Member

    Joined:
    Nov 16, 2010
    Messages:
    3,073
    Location:
    arizona
    not from sammi. i get all my pre-1993 pressure data from the speer reloading manual number eleven (was going to type 11, but thought it might confuse someone).

    the max pressures (in c.u.p.) are in each of the cartridge info page.

    murf
     
  4. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    Can you list a couple of the pre-93 pressures that approximate factory, please?

    I generally get rid of my older reloading manuals when I get new ones, but I did keep my Speer Number 3 from 1959. There's no pressure listed in it, and only cast bullets for handguns. (I was a little young to reload but I used this manual when I started a few years later with a 1917 Colt.)
     
  5. ArchAngelCD

    ArchAngelCD Member

    Joined:
    Nov 25, 2006
    Messages:
    22,122
    Location:
    Northeast PA, USA
    I'm not following the "change in testing methods" argument. Even if changing over to piezo electric testing showed pressures were higher than when testing with copper crush method of testing why would that trigger lowering the pressures? I could understand lowering the powder charges to lower the pressures read by piezo electric testing down to where they should be but why would you need to lower the limits? :confused:
     
  6. murf

    murf Member

    Joined:
    Nov 16, 2010
    Messages:
    3,073
    Location:
    arizona
    jaywalker,

    it would be easier for you to give me a cartridge, or a list, first.

    archangelcd,

    who knows what goes on in the minds of men. i'm sure they had their reasons: political, most likely. can you say 40 s&w and 357 sig (over did it with the 10mm)?

    the only two rifle cartridges with a drop in max pressure: 270 win and 222 remington. all others stayed the same. go figure!

    murf
     
  7. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    Except they started calling the standard pressure .257 Roberts +P though.

    rc
     
  8. murf

    murf Member

    Joined:
    Nov 16, 2010
    Messages:
    3,073
    Location:
    arizona
    the standard pressure for the 257 roberts has always been 45,000 psi (they did not use the "c.u.p." designation back then). this is per the speer number 11 manual.

    the 257 roberts+p pressure is 50,000 c.u.p. the 257 roberts pressure is 45,000 c.u.p. this is per the sammi voluntary performance standards of 1993.

    murf
     
  9. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    ArchAngelCD,
    SAAMI is an industry association and members all agree to abide by the pressure limits set. This allows gunmakers to know what pressures to build firearms to and us to be sure the cartridge we've bought won't be either a squib or a bomb when we squeeze the trigger. SAAMI serves as a clearinghouse for industry's wishes, not a governing body, so once industry has decided, SAAMi publishes a new standard and members (and probably others) load their cartridges to it.

    murf,
    Just the pre-1993 standard pressure for the 357, please, if you have it. I've read anything from 45,000 to 47,000 cup.
     
    Last edited: Dec 28, 2012
  10. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    https://groups.google.com/forum/?hl=en&fromgroups=#!msg/rec.guns/S_dalM1NJe0/cBSU4bR2jz8J

    I was so impressed with this 1993 post that in 2005 I tapped John to help me prove the load books were wrong about the CZ52 vs the Tokarev strength.

    I sent him ~ a dozen CZ52 barrels and he tested them for RC hardness at JPL.
     
  11. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    Clark,

    That's interesting. Can we assume from that that the J-frame 357's five-shot cylinder allows for greater cylinder wall thickness than the six-shot cylinders of the old Models 19/66?
     
  12. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    Jaywalker,

    Model 60 J frame 5 shot 38 sp I reamed out to 357 mag:
    .058" to the outside
    .108" between chambers
    1.308" cylinder diameter
    1.535" long cylinder
    .250" x.090" slots in cylinder for bolt

    Model 66 K frame 6 shot 357 mag:
    .084" to the outside
    .075" between chambers
    1.456" cylinder diameter
    1.675" long cylinder
    .275" x.105" slots in cylinder for bolt

    The 357 mag cartridge could be 1.59 long and the rim could be as short as .049" so the cylinder should be at least 1.541" long

    I have blown up enough cylinders on 38 specials and 32 S&W Longs to know that both the between cylinders AND the to outside thickness must both break. That would mean they add for strength, like ropes in parallel.

    J frame = .164" sum for strength calc
    K frame = .159" sum for strength calc

    It is going to be real hard to blow up either. What happens with smiths is that the slots in the cylinder or the slot in the frame get sloppy. That makes the cylinder loose like a Ruger in rotation, not tight like a post 1907 Colt. The S&W model 29 44 mag got bigger slots in later dash numbers to beef it up.
     
  13. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    Clark,

    Just to be clear, are those measurements to the outside of the cylinder the maximum measurements, or do they include the cylinder stop slots? It appears to me the M19/66 has the slots over the chamber proper, while the J seems to offset to thicker metal.
     
  14. murf

    murf Member

    Joined:
    Nov 16, 2010
    Messages:
    3,073
    Location:
    arizona
    jaywalker, for the 357 magnum:

    old - 46,000 c.u.p.

    new - 45,000 c.u.p.

    new p.s.i. - 35,000

    murf
     
  15. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    Jaywalker,
    You are right, I was measuring from the chamber to the major OD of the cylinder.

    I never noticed it before, but the 5 shot geometry does not have the slot over the a chamber. The slots are between the chambers. 6 shot cylinders have the slot weakening the chamber. That is an advantage for 5 shot strength.
     
  16. CraigC
    • Contributing Member

    CraigC Member

    Joined:
    Jan 27, 2006
    Messages:
    14,744
    Location:
    West Tennessee
    I don't think you can ascertain a cylinder's strength by measurements alone. Particularly if you are not taking into account the location of the bolt notch in relation to the chambers. Because this is almost always the weakest point.
     
  17. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    CraigC
    I could do a thin wall formula for stress, and maybe a Lame's formula for thick wall, but to do it right you would need one of Roark's open end tube formulas. In all three the stress goes up proportional to the inside diameter.

    So at the cave man level, I have tried to blow up many guns.

    I don't care if the gun is 150 years old or new, unless it is a Ruger 454 made of specialty steel, this is my guideline for 3/8" to 1/2" inside diameters:
    .100" thick, I can't blow it up.
    .050" thick, blowing up is easy.

    I bought a 90 year old 32-20 revolver Thursday. It is .136" between and .120" to the outside. The inside dia is .356"

    SAAMI is 16kcup.
    I have not shot it yet, but...
    I can tell by looking at it that in a work up it will pierce a CCI450 small magnum rifle primer [the toughest I have found] before it will burst the chamber.
    That should be 80 or 90k.
     
  18. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    Clark,
    Well, if I read John Bercovitz's formulae right, the M19/M66 cylinder slot cuts are less a yield strength issue than a Young's Modulus inconvenience. It probably only added to the extraction issue he already noted. The numbers don't lie, though - the K-frame cylinders aren't as strong as the J-frame. I'd read about the K forcing cone problems, but this one is new to me. Thanks.

    murf,
    Thanks. Only a 1,000 cup, then. I would think we'd get that much variance from how deeply we seat or crimp, or how hot the day is. Hardly seems worth the effort. I appreciate your looking.
     
  19. CraigC
    • Contributing Member

    CraigC Member

    Joined:
    Jan 27, 2006
    Messages:
    14,744
    Location:
    West Tennessee
    So there is no consideration of the alloy used or its heat treatment??? This is a dangerous game you're playing and I hope everybody reading this thread understands that.
     
  20. Deer_Freak

    Deer_Freak Member.

    Joined:
    Dec 20, 2012
    Messages:
    662
    Location:
    North Carolina
    I am glad all these problems apply to S&W. I have seen people use ruger only charts, then add a little more. The only thing that happened is the gas check failed (in the bullets we were able to recover). I realize that the gas check failing causes leading and in time a loss of accuracy. But nothing happened that would cause a catastrophic failure.

    I have only seen people do this with cast bullets. I have no idea what, if anything would happen to a jacketed bullet.
     
  21. Jaywalker

    Jaywalker Member

    Joined:
    May 28, 2003
    Messages:
    896
    Location:
    Texas
    CraigC: http://www.engineeringtoolbox.com/young-modulus-d_417.html

    Sorry, posted before I finished. Clark is much more qualified than I am to respond to this, but pending his response, here's my quick take:

    Young's Modulus is just a ratio, and it applies to many material, not just steel, as shown on the linked page. As far as alloy of steel goes, it just doesn't make much difference. It might be a small number followed by 6 zeroes, so you're dividing some number by 25,000,000, 29,000,000, or 35,000,000. The difference is nearly too small to measure, and not enough to worry about in revolver cylinders.

    I'd be interested read Clark's take on heat treating, but if anything I would expect it to improve the situation.
     
    Last edited: Dec 29, 2012
  22. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    Oi, am I not qualified. I inherited gun design books, but not gun design brains. I designed electronics. Some gun electronics, but not the gun. I modify guns for fun.

    They don't do much heat treat on revolver cylinders, usually.

    All the 38 specials I reamed out to 357 mag were soft.

    If you try to make a gun, you want some heat treat so it can be light. But hard metal is not easy to machine. And heat treating after machining can be a problem with warpage.

    So there is a trade off. .. except the Ruger 454 that they just wanted to ream out a 44 mag design paper thin and then have really high proof loads. They split cylinders and blew out forcing cones until they found a specialty stainless steel that was economical to machine and strong too.

    Most of the time over the last century when making revolvers, they took something like 4140 steel that would be RB86 80ksi fully annealed, but they buy it hardened to RC29 132 ksi tensile strength.

    Put RC29 4140 in your lathe or mill and it machines ok with coolant all over it. If you ever let a spot get hot, the steel turns very hard and wrecks your tool Then you must try to cut out the hard spot with carbide.

    4140 can be hardened to ~RC60 ~ 300 ksi strength, but that is not your firearms chamber. My father called out 4140 in coil springs for gun designs. I think some chisels are made of it. So in other applications 4140 is very hard. But not in revolver cylinders.
     
  23. WardenWolf

    WardenWolf member

    Joined:
    Nov 11, 2008
    Messages:
    5,884
    Location:
    Northern Virginia
    Ruger has been the true king of revolvers for many years now. Smith & Wesson is largely stuck in the past, and hasn't improved anything beyond their triggers. Their standardized frame system leaves no room for major innovation, as anything new they make has to fall within dimensions that were defined more than half a century ago. Other manufacturers are free to innovate at will, and come up with completely new designs as needed. Only Smith & Wesson has shot themselves in the foot this way.
     
  24. Clark

    Clark Member

    Joined:
    Jan 3, 2003
    Messages:
    4,292
    Location:
    Where I5 meets the rain forest
    WardenWolf,
    I am nobody in the world of revolvers. My father did design a 115mm six shooter for the marines in 1960, the XM-70. "X" means experimental, and we never got much money. The patent on his 6 shot revolver
    http://www.freepatentsonline.com/4353285.pdf
    That patent does publish the formula for parabolic taper hydraulic recoil, that before he did the math on his M55 design, the tapers were determined empirically since the French invented it in WWI.
    Anyway, I own ~ ~ 50 revolvers, mostly bought for testing.
    ~10 years ago I got (5) Colt Police Positive revolvers as police surplus for destructive test. I was really shocked by the quality of the design. I could not shoot them loose.
    I bought a Ruger blackhawk ~5 years ago and fired one shot. I was impressed negatively. I have not pulled it out of storage since. I also have a security six, which seems like a better gun.
    I don't doubt that Ruger revolvers might take over the world, but this nobody likes Colts.
    There is a poster on the firing line that makes amazingly good posts about gunsmithing almost all guns. He was a trained watchmaker before he became a gunsmith.
    Dfariswheel May 9, 2001, 03:24 AM
    Posts: 6,394
    Colt was always seen as the Rolls Royce of handguns. Colt spread their dollar around on the gun, pretty equally on the outside finish, and the inside. Smith & Wesson spent their's on the outside, with a great blue job.

    I think if you research the posts made by Dfariswheel, you will see HE is intrinsically somebody.
     
  25. ArchAngelCD

    ArchAngelCD Member

    Joined:
    Nov 25, 2006
    Messages:
    22,122
    Location:
    Northeast PA, USA
    I'm very confused as to what you are talking about? Not that I care what anyone thinks about S&W but what you said confused me. S&W has come out with the X frame which is different than the others. They also developed the Bodyguard 38 which is completely different than any other revolver ever made for several reasons. It also has an integral laser which is different too. They were also the first to make 7 and 8 round centerfire revolvers. Please clear up what you meant, I'm curious...
     
Thread Status:
Not open for further replies.

Share This Page