Help! Baffled by High Pressure Signs

Discussion in 'Reloading' started by azsugarbear, Aug 20, 2011.

  1. azsugarbear

    azsugarbear Well-Known Member

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    I have a semi-custom 243 Win. that is built on a Rem Model 7 action. It wears a Brux fluted barrel chambered in PTG's 243 Tactical Match with a 1 in 9 twist. Action is bedded in HS stock. Leupold 4-14x40 scope.

    At this point, I should probably mention that I have been reloading for 25+ years. During break in of barrel, I loaded and tried several different powders in my Lapua brass. I shot the following ladders with the 105 gr. Berger VLD:

    H4831sc - 40.0 to 44.0 grains* (settled on 42.5 gr. @ 2,860 ave. fps)
    H1000 - 43.0 to 46.5 grains* (settled on 45.0 gr.)
    H4350 - 37.0 to 41.0 grains* (settled on 41.0 gr. @ 2,930 ave. fps)

    * all loads are within min and max load range recommended by Berger

    Shot drop chart w/41 gr. of H4350 - went hunting. At this point in time, I had 150 rounds down the barrel. Never fired a shot during hunt, but I did drop my rifle (not a bad drop at all). I decided to re-zero scope the following week. When I went to the range, I noticed that the same loads were now giving me a sticky bolt and some signs of pressure (cratering & extractor marks).

    I started to recheck my loads wondering what was going on. All the previous loads with different powders were now showing excessive signs of pressure. I thought it might be the warmer temps, so I kept rounds in fridge/cooler prior to shooting. I double checked the weight of each charge on two different scales. I went back and checked my max COL and then backed off another .02". I reconfirmed case length was within specs. I cleaned the barrel using both BMG 50 and Wipeout to ensure there was no copper build-up. Nothing has helped.

    This morning I went back to the range. I shot one round of 45.0 gr. of H1000 pulled from my cooler. I experienced serious bolt stick, with cratering and extractor mark on case along with a chrony speed of 3,021 fps (it should have been around 2,900 fps). Rather than shoot the other two, I switched to a cooled round of 38.0 gr. of H4350. This shot resulted in a stuck case where the bolt had to be pounded open with a mallet. The primer had been completely blown out of the pocket with a heavy extractor mark. The chrony showed a reading of 3,063 fps, when it should have been in the 2,750 fps range.

    I am completely baffled! Where do I go from here? Is it possible that something happened to the bolt/action/barrel when it was dropped? Any ideas?
     
  2. Johnboy

    Johnboy Well-Known Member

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    at any time did you have to change lots of powder.or did you have to use a new pound of the same.this may be the case for you.just what came to my mind for an answer.cannot see that dropping the rifel would have done anything.but who knows these days.

    or the case lengths could have been off to some degree.or the shoulds didn't get bump back like you wanted them to be.thats if you have to bump them back at all.you didn't say to how you resiszed the brass.

    or you may have changed primers like a mag coud have been used.just putting out ideas to what happened.the only other thing right now that comes to mind would be a temp change.maybe some one else will chim in soon
     
    Last edited: Aug 20, 2011

  3. azsugarbear

    azsugarbear Well-Known Member

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    Johnboy,

    Thanks for responding. No change in powders. All loads came from same canisters as previous loads.

    Case lengths were trimmed initially with RCBS case trimmer as part of case prep. They have only had 2 firings each. I full length resize each case. There was no resistance when closing the bolt or chambering a round. I have rechecked the length of the brass, with all of them at or under specs.

    The primers might be a remote possibility, but I am usually very careful about using the same ingredients when reloading. No chance of a mag primer, but it is remotely possible to have switched from a Federal to a CCI. I would expect some small difference between different primers, but enough pressure to make the round climb over a couple hundred fps?

    I gotta tell ya - this one has me stumped.
     
  4. Johnboy

    Johnboy Well-Known Member

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    OK we worked tose ideas out.so we need to think of more.

    could it be that you may have trickled a little more powder in on a few loads.did you load alot when you loaded these rounds?just asking because when I load I only load 20 or more t one time.maybe less.just depends on the need for what I am wanting to do with that rifel I am loading for.I guess what I am trying to say is that looking at the scale beam or dig can make my eyes go fuzzy at times.or just seeing 45.00 or looking at the beam alot will play with my eyes.

    we have broke it down.the really best ideas are not the case for this to have happened.the only other would be a added amount of powder I would think.OK just thought of this.my mind is working I hope.it might just be the case of the neck haveing more bite on the bullet.( tension )but you did say the cases had only 2 fireings on them.but your chamber is a match chamber.the necks may need turning or reamed.

    OK the brain is really working now.could it have been the case that the bullet was longer( closer to the lands.or that it might have been shorter closer to the charge.either can cause a spike.just depends on how close the bullet was to the lands in the begining.

    OK just read your post again.this is all the brain can come up with.if it is the case that by dropping the rifel its something I do not know at all.I really think we have covered it.but again who knows.still want to know though.learning is the best thing in this world.( reloading )

    some one else we need you ideas.so chim in.
     
  5. azsugarbear

    azsugarbear Well-Known Member

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    Johnboy,

    I really appreciate you taking a stab at this.

    I hand weigh each charge before dumping it into the case. After yesterday's disappointment at the range, I cam home and pulled the bullets on the other two rounds loaded with 38.0 gr. of H4350. I re-weighed both charges: first on the Redding 10-10 balance beam scale, and then on an electronic scale. All four readings came back at 38.0 grains. Because I am experiencing pressure with several different powders, I don't think it is due to weighing or powder volume.

    I do like your idea of checking the necks! I had checked them for length, but not for thickness. At this point, I think I will pull all the bullets loaded for my tests and then resize them. After that, I will turn all the case necks down, reload a few and see if that makes any difference. It may not help - but it certainly won't hurt. After all, its just time spent. Thanks for the idea.
     
  6. SYee

    SYee Member

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    Az,
    I will throw an idea out there, did you check to see if the loads were the same length as the previous test loads, longer and shorter might cause the spikes you are seeing.

    Just an idea.

    SY
     
  7. Johnboy

    Johnboy Well-Known Member

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    hey just trying to help out a fellow shooter.its got my attion all so.thats why sites like this one can help out many of us.maybe after we fix you problem some one will have the fix for them one day if the same happens to them.

    just keep us posted as you tyr to get it.will keep my brain at work for ya.as of now its blank.
     
  8. sr5

    sr5 Member

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    Sounds like you might have a carbon problem. Was through this same situation a few years ago. Same bullet and powder from same lot and all of the sudden I was blowing primers. It took a swabbing with jb bore paste especially around the throat area and the high pressure problem went away. A general cleaning generally wont take that carbon ring out. You have to attack it with carbon specific cleaner to get it out. Hope this helps
     
  9. azsugarbear

    azsugarbear Well-Known Member

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    Thanks for the suggestions:

    Johnboy suggested turning my necks (which I have now done). I have loaded some new rounds up, but have yet to shoot them.

    I will also scrub the neck area with a carbon cleaner and see if I get any color. I use a bore guide, so it is possible that the guide is just long enough to cover, or butt up against the ring and not allow my brush and solvents to do their job.

    I will let you know the result in a week or two when I get out to shoot them.
     
  10. BountyHunter

    BountyHunter Writers Guild

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    Changing primers can increase pressure up to 5000 psi measured with strain gauges

    I would bet on a primer change or the carbon ring

    The ring will take some scubbing aLso

    BH