Help identify preasure signs ?

Discussion in 'Reloading' started by dustybrown, Jan 30, 2010.

  1. dustybrown

    dustybrown Well-Known Member

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    I have been handloading for about 3 years and have ALOT of fun and some sucess with my 22-250 and .243...in the last 6 months I have been loading for my 300 RUM. Its a lilja bbl 700 rem. I have played with rl-25 and retumbo and the 185 berger vld. cci 250 primers or fed 215's. neck sized rem brass at 3.68 coal. still fits mag. I have a brake on it and it still feels like some one punching me in the face when i shoot it. I can get past that recoil and im sqeezing of good shots, i guess... its shooting .7 " at 200. Im hitting fair at 850 yds.. My little experience with big charges has me scared to increase. Im running 94 grains of retumbo and the max listed by bereger is 96 gr. I know what to look for but ive never seen any preasure signs to know what it looks like. ???? (you get where im going yet ?) I know to look for primer flow and ejector marks but don't know what those look like... It's simply a confidence issue with my experience level. My MV with the 185 vld is 3060 to 3073 with the 94 gr. charge. Thats not letting me get to 1000 yd. with one rotation on my scope. 70 1/3 " clicks is well into the second rotation at a grand. I was told to try to get my MV to up around 3200 fps. this would also let me use less wind hold. any advice would be appreciated.. Thanx
     
  2. MontanaRifleman

    MontanaRifleman Well-Known Member

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    My number one pressure indicator is how well the brass holds up, specifically the primer pockets, but that doesn't help much at the bench when you are working up. I keep an eye out for ejector marks and flattened and cratered primers along with a sticky bolt. Every rifle and load seem to show signs a little different. With my 700 Sendero 300 RUM I sometimes see ejector marks a grain or so before I see other signs. Flattened and slightly cratered primers tell me in right on the edge and when I get a sticky bolt, that means back off. When I run a half grain below a sticky bolt, my primers are fairly flat with some very light cratering and an occasional ejector mark , but my primer pockets in my Rem brass hold up OK and my bolt moves freely. It's what I consider a "warm" load.

    There can be other reasons for sticky bolts, flat primers, etc. and it's possible to get over pressure and miss the signs so you need to be careful. Im my experience, my rifle has always told me when it was time to back off.

    Mark
     

  3. RockZ

    RockZ Well-Known Member

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    I just did some load development with my 6-284 built on a Savage target action.
    When I measured the case head web area, I notice that up to .0015" greater than original case diameter still results in smooth bolt operation.
    When it gets to .0020" I get noticable increase in bolt lift as well as a small ejector mark.
    I will keep my charge at or below whatever charge gives me .0015 case head expansion on the first to second firing.
     
  4. yama49

    yama49 Well-Known Member

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    Any pics of ejector signs, I also have not worked a load up to max( havent had to). But i would also like to learn about it.
     
  5. MontanaRifleman

    MontanaRifleman Well-Known Member

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    \

    On the Rem 700 it will be a bright shiny spot near the edge of the brass head. You'll know it when you se it.
     
  6. MontanaRifleman

    MontanaRifleman Well-Known Member

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    Something to keep in mind is that a lot of powders show increased pressure with increase of temp. If you work up a load in cool weather, it's probably a good idea to back off one or two grains and then give it another look in warm weather to see where your warm weather threshold is.
     
  7. J E Custom

    J E Custom Well-Known Member

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    There are several good indicators . The first is any bright places on the case head. This
    is normally caused by the case head being pushed into the the ejector hole and then when
    the bolt is operated it scrapes of some of the bulge leaving a round bright spot on the case
    head the same size as the ejector .

    Different primers will flatten differently because of cup thickness and hardness, So it is diffacult
    to read them accuratly but if they are smashed flat with no radius on the primer edges it is
    probably on the hot side.

    Normally If you have heavy bolt lift it is hot and should be backed of by 1/2 to 1 grain of powder
    and you will probably see all of the other signs mentioned.

    When you really push them the brass will flow and looks kind of like galvanize but only a
    different color and the cases get longer and have to be trimmed more often.

    Velocity is also another indicator.(If you are getting quite a bit more velocity than the listed
    Max loads) then you are pushing it.

    J E CUSTOM
     
  8. 300rum

    300rum Well-Known Member

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  9. dustybrown

    dustybrown Well-Known Member

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    Thank you much.... I assume as i seat longer it will also change preasure. I am seeing groups that im happy with at 94 grains and for no other reason than performance at ranges beyond 600 do i need to increase MV. But knowledge is addictive.... and so is distance. :D
     
  10. Bravo 4

    Bravo 4 Well-Known Member

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    Yep.
    I have noticed that no matter what the temp is, if I start to get any pressure signs I back off one grain (.338 EDGE and 7mm Rem Mag) and consider that my max. Then I have never had a problem going cold to hot or vise versa.
    Also, try to keep your ammo out of the elements as much as possible (IE- out of direct sunlight).
     
  11. Limbic

    Limbic Well-Known Member

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    First thing I look for is a shiny circular mark on the head of the brass. Primer flow always occur because the primer hole and primer are extremely different in size. Sticky bolts means I'm way over pressure.
     
  12. dustybrown

    dustybrown Well-Known Member

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    The pictures i found on a search did not help much. The pic of the 38 supper was what I wanted to see. The stuff I goggled was compairing normal with almost catastrophic...thanx again.
     
  13. Clark

    Clark Well-Known Member

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    1) The 1889 Mauser 7.65x53mm case head design, when built with a large Boxer primer and shot in a strong rifle is good for 62kpsi factory ammo and 65kpsi custom hand loads.
    Pressure sign: primers fall out
    Better pressure sign: primer insertion is too easy
    Best pressure sign: extractor groove grows .001" anywhere around the circle
    Examples: 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 25-06, 260 Rem, 6.5x55 [US brass], 270, 7mm-08, 7x57mm, 280, 308, 7.62x51mm, 30-06, 8x57mm, 338F, 358, and 35W.

    2) The 1950 designed .222 case head with small rifle primer is good for 75 kpsi with custom handloads
    Pressure sign: primers fall out
    Better pressure sign: primer insertion is too easy
    Best pressure sign: extractor groove grows .001" anywhere around the circle
    Examples: 17 Rem, 204 Ruger, 221 Rem Fireball, .222 Win, .223 Win, 5.56x45mm, .222 Rem mag, 6x45mm.

    3) The 1889 Mauser 7.65x53mm case head design, when built with a small primer and shot in a strong rifle with bushed firing pin hole is good for 85kpsi custom hand loads.
    Pressure sign: primer pierces
    Better pressure sign: extreme cratering of primer
    Examples: 22BR, 6mmBR, 6x47mm, 6.5x47mm, 7mmBR, 30BR, Lapua small primer 308