1. Attention: We have put together a thread with tips and a tutorial video to help with using the new software. Please take a moment to check out the thread here: Trapshooters.com Tutorial & Help Video.
    Dismiss Notice

So what's considered excessive pressure?

Discussion in 'Uncategorized Threads' started by hoggy, Sep 7, 2008.

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

    hoggy TS Member

    Joined:
    May 9, 2006
    Messages:
    1,261
    With all the talk and articles on blown barrels I'm wondering (after doing a quick search with no answer) what is considered excessive pressures. I know loading low pressures is no good either so what is the best pressure range to reload in? As an example does anyone know know what pressures loads like Nitro 27's are or AAA's?
     
  2. waverider

    waverider Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    1,631
    Location:
    HI
    Maximum working pressure for 12 ga 2 3/4" shell is 11,500 psi.

    My feeling for the best working range is 9,000 to 10,500 psi.

    I too would like to know if anyone had the new Nitro 27 and/or AA HCP rounds tested.

    I would guess that the new Nitro 27 would be right about the maximum of 11,500 psi. When the new Nitro 27 came out a Hodgdon rep stated that Rem was using retail version of TiteGroup. Cutting a part a few shells showed that the powder weight was about the published recipe. Remington now uses a wholesale version and develops loads per the lot of powder they buy, powder looks like TiteGroup but the weight does not match any more.

    Jason
     
  3. Shooting Coach

    Shooting Coach Well-Known Member

    Joined:
    Sep 14, 2006
    Messages:
    8,358
    Location:
    Nashville Tn
    Posted SAAMI maximum pressure for the 12 ga standard shell is 11,500 PSI. Be mindful the factory is loading NEW brass. We are using fired brass, often fired in another gun and resized.

    I consider minimum 8000 PSI and maximum under 10,000 PSI. I will not recipe a load with pressures over 10,000 PSI. I have had best results with loads at or near 9000 PSI.

    Using Unique in my Caps load, I get a little under 9000 PSI while still getting over 1250 fps out of a full 1 1/8 oz.

    I have gone to Promo for 3/4 oz loads at 1200 for new and petite shooters, 24 gram Bunker loads at 1350, and one ouncers at 1250. Thanks, Alliant.
     
  4. ricks1

    ricks1 TS Member

    Joined:
    May 7, 2007
    Messages:
    1,545
    if you dont a way to check the pressure the next best way is to look at the primer. Take 2or 3 factory fired shells and look closely at the primer look at the edges where it meets the cup. This needs to be on a gun that is not an AUTO. O/U or pump I had a post that was wanting to know how you could get 3/4 oz in a 410. Win has a 3/4 load The books list one with 15gr H110. I emailed Win and they told me everything but the powder Said it was FACTORY stuffm but said to look at Hodgens 110. So took one apart to see they uas a powder that look like and burns like H110 so i think it is 110 BUT there is only 12gr in it. The primers are very flat[fired in a single barrel] Now i found yes you can load 3/4oz in a NEW win hull with 12gr but you cant in any other hull I have not shot enough of them {they are $22 abox] to know but the [NEW] hull is paper thin. You can get 3/4 if you cut the petles off the shot cup in fed and rem BUT 15gr is way too hot 3 out of 5 the brass split. rick
     
  5. halfmile

    halfmile Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    15,648
    Location:
    Green Bay Wisconsin
    The heaviest .410 loads I have found are for 11/16 oz.

    15 grains of H110 is for a half ounce, a standard skeet load.

    NO damn wonder the brass split. You were 50% over on the shot charge.

    What flincher said.

    HM
     
  6. Quack Shot

    Quack Shot Active Member

    Joined:
    Mar 14, 2006
    Messages:
    4,003
    Lot's of misconceptions out there. Primers are not a reliable indicator of pressures in a Shotshell, EVER. As far as Pressures are concerned, I'll go within the boundaries that Shooting Coach has stated. 8000 - 10,000 PSI. I'll also limit the top end to about 9500 LUPs, if that is the method used. I know there is no comparison, but that seems to be about the point where quite a few loads hit the 10,000PSI mark. It's not that accurate, but it will work for me. Remember these loads are being shot repetitively in a target gun over a long period of time. It is the cumulative stress on a firearm that can create some catastrophic failures. Not just that one "Special" overloaded shell. If the gun is already weak, that one shell can do it, but according to the experts at HP White Labs, it is also cumulative stressors over time. A moderately overloaded shell will eventually damage a firearm if you shoot enough of them, even though they appear to work fine. A few thousand of those "Magic" back fence loads could do it! When the failure occurs, it was just the last stressor that did it in and pushed it past the limits that have slowly been reduced over time for that firearm. It does NOT have to be an overloaded shell that was fired when the gun failed. The gun had actually begun to fail well before that point. Grab the first two PDF files at the link above and read the documentation. It's a good discussion of catastrophic failures and related info.
     
  7. SMITH47

    SMITH47 Member

    Joined:
    Aug 21, 2008
    Messages:
    561
    when i go to the Hodgdon powder data web site for 28ga. with universal powder and win primer, 3/4 oz shot, it lists psi from 11,500 to 12,400 depending on the wad. this is higher than the 10,000 that is being discussed here ?
    help !

    ernie
     
  8. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,849
    ANSI/SAAMI Z299.2 (1992) lists for 2 2/4 1i ga.

    Maximum average pressure: 11,500 psi

    Maximum probable lot mean: 12,100 psi (a calculated figure)

    Maximum probable sample mean: 13,000 psi (a calculated figure)

    Proof loads are 19,000 to 20,500 PSI

    Neil
     
  9. Shooting Coach

    Shooting Coach Well-Known Member

    Joined:
    Sep 14, 2006
    Messages:
    8,358
    Location:
    Nashville Tn
    The industry 11,500 psi max is for 12. The 28 and 410 are loaded to higher pressures. I still like to limit pressures in the small bores to 10,000 PSI max. Slower powders and primer/wad combos can do this.
     
  10. ricks1

    ricks1 TS Member

    Joined:
    May 7, 2007
    Messages:
    1,545
    look up the loads for the 410 they call for a 16gr H110 on the 3/4oz in the Lyman book i single is 10 times stronger than others rick
     
  11. Bruce Em

    Bruce Em Member

    Joined:
    Jan 29, 1998
    Messages:
    902
    Location:
    Upstate NY
    What bursts the bbl? It isn't "pressure" it is stress in the metal above either a) the yield point or b) high cycle fatigue (embrittlement). Any given metal has material properties for yield point stress so the variables you have to work with are pressure, tube diameter, and wall thickness.

    Hoop stress in a cylinder is proportional to pressure times diameter /2* wall thickness. So small gauges can get the same stress at higher allowable pressures. The industry allows for that with higher allowable pressure for smaller gauges.

    BTW, Hoop stress is twice the longitudinal stress. This is also why the hot dog rip along the length and doesnt burst "in half"

    regards
     
  12. Quack Shot

    Quack Shot Active Member

    Joined:
    Mar 14, 2006
    Messages:
    4,003
    SMITH47

    We were discussing 12ga loads and their desired pressures. Smaller gauges would have different pressure limits. I would still recommend staying below the listed maximums for the sub gauges. I don't like to push my luck or stress my firearms needlessly. In the 12ga it is as simple as selecting the right combination to achieve the desired velocity and stay within the band of pressure discussed here. A powder or primer change can be all that is needed to keep the pressures down.
     
  13. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Neil gave us some very interesting data.

    Maximum average pressure: 11,500 psi

    Maximum probable lot mean: 12,100 psi (a calculated figure)

    Maximum probable sample mean: 13,000 psi (a calculated figure) Proof loads are 19,000 to 20,500 PSI

    This tells us that with an average pressure of 11,500 psi, the variance in the mean pressure could be over 1000 psi (probably calculated as mean +- 1 SE).

    If proof pressures are 20,000 psi, would it be logical to think that somewhere around 25,000 psi is required to damage a well made gun?

    Pat Ireland
     
  14. spritc

    spritc Active Member

    Joined:
    Jan 29, 1998
    Messages:
    1,483
    Location:
    Indiana
    When your whole body is lifted off your chair.
     
  15. Bruce Em

    Bruce Em Member

    Joined:
    Jan 29, 1998
    Messages:
    902
    Location:
    Upstate NY
    Proof says it survived one, or is it two "blue pills"

    How many proof loads before you get cyclic fatigue failure? Not many I bet.

    The lower the peak pressure, the more cycles allowed before crack initiation

    regards
     
  16. Gary Waalkes

    Gary Waalkes Well-Known Member

    Joined:
    Jan 5, 2007
    Messages:
    1,401
    Before getting too wrapped up, remember that the barrel is not supposed to be plugged or even partially blocked. If you remember the thread, Mr. Bowen tried to blow up an inexpensive gun with just overloaded shells and was not sucessful.
     
  17. Quack Shot

    Quack Shot Active Member

    Joined:
    Mar 14, 2006
    Messages:
    4,003
    Gary,

    If I'm not mistaken, Bruce Bowen actually did simulate barrel obstructions and I also believe he did the 20ga in the 12ga chamber trick. That H&R did take a beating. I'll have to search for the thread. I will agree that a significant barrel obstruction could be a cause of a rather spectacular catastrophic failure.
     
  18. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,849
    Pat, I think that the answer to your question

    "If proof pressures are 20,000 psi, would it be logical to think that somewhere around 25,000 psi is required to damage a well made gun?"

    is "no, it is not logical to think that." You would need 25,000 psi test loads to find that out.

    What is logical to think is that a gun which "passed proof" was not blown up by a proof shell, and probably won't be blown up by the next one either, and so, if it has a flaw in its metal, it hasn't shown up yet though it's been given a good chance to.

    Neil
     
Thread Status:
Not open for further replies.