Pressure signs way below max load

Discussion in 'Long Range Hunting & Shooting' started by Mc Fraser, Aug 17, 2019.


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  1. Clem Bronkoski

    Clem Bronkoski Well-Known Member

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    I'm not sure if anyone has brought this up or not. I didn't read all the posts. But I had just purchased a Hornady lock-n-load gauge for getting an accurate reading for my intended bullet seating depth. I was reading the instructions and noted that if you bullet does not have significant jump you may experience spikes in pressure. Maybe this is what you are experiencing. I don't know, just throwing this out there.
     
  2. Mc Fraser

    Mc Fraser Well-Known Member

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    The firing pin spring made a small difference. Smith is working on the bolt now.
     
  3. Lycanit

    Lycanit Well-Known Member

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    Good to hear, did he give you any specifics and still what he felt the firing pin diameter vs hole diameter was?
     
  4. Mc Fraser

    Mc Fraser Well-Known Member

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    We didn't talk much, he said he wants to put a bushing and I gave him the bolt. I trust him so I don't really question him.
     
  5. LazzInc

    LazzInc Official LRH Sponsor

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    I am not sure that I could see 3100 fps out of a 300win mag shooting 215gr bullets anywhere near a maximum of 66,000 PSI pressure no matter what powder I was using ,,,, and with a tighter twist than 10, the max velocity will be down even a little further ,,,, if my memory is right, you should be getting around 3000-3100 fps shooting 180gr bullets out of the 300WinMag ?
     
  6. Mc Fraser

    Mc Fraser Well-Known Member

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    I don't remember trying 180 bullets with labradar. I want to shoot at least a 200gr to have some power at long range. There is something wrong with my rifle, im sure of that ... we will see how its shoots after the bolt is done.
    I wonder if I screw it up trying this hot loads ... I'm not even sure if the loads are hot, I suspect the increase in velocity is due to the long barrel 29in but a longer barrel does not mean increase pressure, assuming everything else is equal. Most guns are fine with 1gr over the book max, especially that the new books are lawyer proof with safety factors.
     
  7. kiwikid

    kiwikid Well-Known Member

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    Did you ever weigh any of your Norma cases?
     
  8. Mc Fraser

    Mc Fraser Well-Known Member

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    Yes, when they were new. Where are you going with this question? :)
     
  9. kiwikid

    kiwikid Well-Known Member

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    Norma made some 300 Win cases that weighed more than normal. Please have a look at my post No 89.
     
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  10. T3ninja

    T3ninja Well-Known Member

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    Maybe I’ve lost track so clear this up for me and the others here. Thread title “ pressure signs way below max load”.
    Post #1 says
    “I constantly see pressure signs 1.5 to 2.5 grain below max load with with different powders and bullets.”
    Now, post #118 say “ I wonder if I screw it up trying this hot loads” “ Most guns are fine with 1gr over the book max, especially that the new books are lawyer proof with safety factors.”

    What charge weights are you using with each powder? How is your seating arrangement? (How far off/into the lands)?
    How heavy is your Norma brass? I’m lost on this thread because so many questions have been asked, not all have been answered, and the information is all over the place.
     
  11. Orange Dust

    Orange Dust Well-Known Member

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    I'll chime in here with what I know. First, velocity is also an indication of pressure. If it is higher than it should be, most likely pressure is also. Next, I haven't seen this mentioned, is a new bullet at least a slip fit in a fired case with no binding? If not you need to turn the necks on those cases. Last, if you have a carbon ring you can easily remove it with Isso, but be careful with that stuff. There are several threads on how to do it right. The high ES you are seeing tend to make me think it is one of these three things.
     
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  12. Mc Fraser

    Mc Fraser Well-Known Member

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    All my Norma cases are 215gr. TY

    I call them hot loads because I see pressure signs. I’m puzzled because I see these pressure signs at ~2gr below what new books consider max load, old books go even higher.

    Yes velocity is indication of pressure. My question: between 2 identical rifles one with 30 in barrel and second with 26in barrel shooting the same cartridge the rifle with 30in barrel will see a speed increase. But it will see a pressure increase as well? If yes, why?
    I doubt the root cause is the case. I use Norma and Hornady brass both yield same results.
    Smith says carbon tings have nothing to do with pressure.
     
  13. Orange Dust

    Orange Dust Well-Known Member

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    Carbon rings can be a contributor to the high ES's you are seeing.
    Remember, Velocity increase is not linear. 30" should be higher than 26" with heavy bullets and slow powders, but adding 4" To a 26" may not add any more than adding 2" to a 24" if that makes sense. You are seeing velocities that I see with my RUM and a 26" barrel. Pretty high for a WM with any barrel length. The only way it would see increased pressure is from a secondary pressure spike that sometimes happens with combinations slow powders and specific bullets. Don't think it would be consistent with different powders or bullet weights. Bushing the bolt to a smaller dia firing pin, and a heavier spring may allow you to operate at those pressures without cratering and piercing primers, but it will not change pressure.
     
  14. Mc Fraser

    Mc Fraser Well-Known Member

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    I did a test where I loaded one bullet at min charge from the book, it was 200gr ELD-X, 65.4gr of IMR 7828. Again I've seen pressure signs, not as bad as before with higher powder charge. Now I'm leaving my rifle in the hands of my smith. I might consider chopping the barrel to 26in after I test the bolt. This is very interesting and I'm curious to see the outcome.