1st time pressure test

Discussion in 'Reloading' started by bob4, Sep 23, 2018.

  1. bob4

    bob4 Well-Known Member

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    Being relatively new to reloading, 5 yrs or so I finally decided to try and look for pressure signs in my factory Rem 700 300 WM. Only sign I ever had here was bolt lift. Primers were fine and no ejector marks. My first sign was at 76.5 was a tiny bit sticky. Took a bit of a grip to lift the bolt. Not to bad. @ 77gn it took a lot to lift the bolt so I stopped. This was brand new Norma Brass, trimmed, deburred,chamfered and set at .002 tension. Only thing I noticed on the brass at 76.5 and 77 were marks ,scrapes or brush marks if you will just above the belt. Not a lot but noticeable and weren't present on lighter loads.Should I just call 76 my limit? Tried as best I could to get a pic but the brush marks aren't showing up very well.
     
  2. bob4

    bob4 Well-Known Member

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    Magneto speeds:

    74.5...2767
    75......2779
    75.5...2813
    76......2802
    76.5...2876
    77.....2867
     
  3. Mikecr

    Mikecr Well-Known Member

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    If this was NEW brass, then you should back off and work up with the fired brass. Otherwise you could have more pressure OR more of a pressure PROBLEM (key difference).
     
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  4. lancetkenyon

    lancetkenyon Well-Known Member

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    What bullet?
     
  5. bob4

    bob4 Well-Known Member

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    Sorry thought I had that in there. 215 Berger hybrid
     
  6. bob4

    bob4 Well-Known Member

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    So shoot the new brass once first before checking for pressure? Mind educating me on why?
     
  7. lancetkenyon

    lancetkenyon Well-Known Member

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    Brass: Norma
    Primer:
    Powder:
    Bullet: 215 Hybrid
    CBTO:
    Jump/Jam:
    Case growth @ shoulder w. Headspace gauge (new to fired):
    Temperature:
    Altitude/Barometric Pressure:

    Not sure why you would trim new virgin brass except maybe to just square up the neck. All new brass I have ever purchased was at trim to or minimum length already.

    Did you neck size it all prior to loading? How did you come up with .002" neck tension?

    Did you anneal the neck/shoulder?

    How accurate/what type of a scale did you use?
     
  8. couesaddict

    couesaddict Well-Known Member

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    New brass has more room in the chamber than once fired. Escpecially if you do minimum resizing to keep tolerances close. By having that extra tolerance, new brass will soak up some of the energy expanding out to the chamber dimensions and hide pressure signs. My guess is, actual pressure is very similar between once fired and new but I just had a load that performed flawless with new brass in my 300rum, stick with once fired brass. Within 10fps velocity between the two. I backed off another grain and things are shooting fine. Cost me 50fps though.
     
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  9. bob4

    bob4 Well-Known Member

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    Primer: Winchester LMP.
    Powder H-1000
    .040 off lands
    Temp 80.
    Altitude/Barometric Pressure: Sea level +5 or 6 feet ;)
    RCBS Beam scale. I'm fussy about powder weights.

    I trim all brass with thoughts of how much bullet is in the neck. Also shoulders are way under where I bump them at this point. In due time. All of these were run through Forster bushing bump dies to get the neck down then through a mandrel opening them up .002 under caliber. I've never annealed new brass. Have not gotten around to measuring fired brass yet.
     
  10. lancetkenyon

    lancetkenyon Well-Known Member

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    77.0 is over Berger max load. But just about Hodgdon max load (I know the 210s are 78.0gr H1000 max load but don't recall the 215 max). But max in your rifle can/will vary.

    Max case length is 2.620", so trim to length should be 2.610". I wouldn't go much shorter than this, especially since the .300WM already has a fairly short neck to begin with. And I bet your virgin brass was 2.610" or shorter to start. So no need to trim.

    Everything else sounds about right. Your rifle just must max out at 76.0gr. I wouldn't go higher if you are getting sticky bolt lift. Every .300WM I have loaded for using H1000 has been right in the 76.0-78.0 for an accuracy node at the higher end using either 210 HVLD or 215 Hybrids. Just finished loading for one yesterday.
    Nosler brass
    Fed 215 Mag
    77.5gr H1000
    210 HVLD
    2.690" CBTO (Win 70 w. Short mag box, but about a .160" jump is where the rifle liked them)
    2941fps from 26" barrel
     
  11. bob4

    bob4 Well-Known Member

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    Yeah, got the load Data from Berger and they stated is was conservative. Was hoping for a bit higher as most report a node around 77 with this combo. We'll see.
     
  12. tierradelmundo

    tierradelmundo Member

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    The chamber in my factory rem 700, 300 win mag is so long that I actually had to bump up the powder charge by 1.2 grains just to get back into the velocity node after the first firing and bumping the shoulder back .001". If you have an equally sloppy chamber there is literally no point in trying to find anything out with the first firing of the case, just run a known, safe load through the gun to stretch the cases out, then do your load work up with once fired cases. The other alternative is to have a new brass load and a once fired brass load, both giving you the same velocity.

    Personally, I use the expander mandrel to make the case necks uniformly round, then turn the case necks, then use the bushing bump die to set neck tension. I'm not saying you're necessarily doing it wrong, just thought I'd point out that there's another way to use the tools you have.
     
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  13. MagnumManiac

    MagnumManiac Well-Known Member

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    All rifles differ enough, even when using the same reamer, that you cannot assume 2 rifles will digest the same charges.
    I have 2 barrels chambered within .001” of each other running 215’s, one can digest 77gr H1000, the other can take 78gr. If I use 78gr in the 26” barrel, it locks the bolt and has ejector wipes pretty badly. Velocity goes up to over 3000fps with that 1 grain increase. Pressure is in excess of 70,000psi.

    I have recently run into a pressure issue using a load that was safe in new unfired brass that showed excess pressure in the same once fired brass. Pressure was way above normal, primers very flat, ejector marks and swollen primer pockets.
    So, when switching to once fired, if the load was near/at max pressure, it can go over with once fired brass, just keep this in mind.

    Cheers.
     
  14. bob4

    bob4 Well-Known Member

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    Taking advice from here I fire formed 30 cases today. Good reason to burn up powder and bullets you don't use. Shoulders moved .015 bringing them very close to bumping length. I'll clean and resize, back down to 74G and start again.
    One last question on this. The two pieces of brass that showed pressure signs I had trouble with even after full resizing. They slid in OK bolt opened and close was smooth. But sliding the bolt back was sticky on one and worse on the 77G shell. After cleaning with stainless media all returned to normal. What gets fubared when you can't slide the bolt back ?