Load development in 80 + degrees

Discussion in 'Reloading' started by jmason, Jun 8, 2009.

  1. jmason

    jmason Well-Known Member

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    I was using a load I worked up over the winter until about a week ago when it started getting 80+ around here. I was getting pressure signs so I started putting my ammo in a cooler and that worked ok. I wanted to work up a new load in this heat so I did, but what I found was my gun will not tolerate any loads within about a grain of book listed or QL max. Shooting some 130 grain BTs over H4831SC and maxing out around 2950 with my 26" factory tube.

    Would this be normal or should I be looking for something else causing pressure?
     
  2. J E Custom

    J E Custom Well-Known Member

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    What calibre ?

    How close to the lands are you ?

    And one other thing, check the trim length and look at the case mouth of a fired case
    to see if it looks crimped.(You can take a loaded round and see if the bullet will go in
    the fired case easy), Some times a rifle can be chambered with a short neck and it doesn't
    want to release the bullet.

    H 4831 sc is an extreme powder and is not known to be sensitive to temperature changes

    Just a few thoughts on your problem.

    J E CUSTOM
     

  3. jmason

    jmason Well-Known Member

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    Shooting a 270 win., I'm at least .030 off the lands, trim and case length are good. The load I made up when it was cooler was a 140 BT w/ 57.7 of H4831SC. It defiantly cares how warm it is out side. So I figured I'd work something up in the summer heat to shoot in the summer heat.

    This is happening w/ virgin rem brass too(forgot to add that earlier).

    I really don't care if my lot of powder is sensitive or not. I'm just looking for a sanity check. By the sounds of your response you don't see this as something that could normally happen?
     
  4. old_heli_logger

    old_heli_logger Well-Known Member

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    That virgin brass may very well have less case capacity...that will raise your pressure. I'm assuming you developed your load on fire-formed brass...

    Good luck!
     
  5. jmason

    jmason Well-Known Member

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    I think I might be confusing you. I had a load made up from the winter 57.7gr of H4831sc and 140 BTs. When it got warmer out it was causing a heavy bolt lift and smearing the base of the brass as well as leaving a ring from the plunger in the bolt face. If I put my ammo in a cooler and shoot it I have no issues. This load is using the same brass I developed it with which is on it's 8th firing and has been annealed every time since the 4th firing.

    So I decided to work up a load in the warm weather with some 130 gr BT's and H4831sc which started to show pressure signs around 58 gr. which is a full grain under listed max in the book and QL. This is with brand new brass. It is a lighter bullet, but at about the same charge as the 140 gr bullets I begin to see pressure. Now the book load was tested with a 24" shelien barrel and I have a 26" factory. I am getting a heavy lift but no markings on the brass.

    Where the need for a sanity check comes in is I'm thinking the lighter bullet should be able to go faster than the heavy one without showing pressure at the same charge weight. The new load work up is using virgin brass but I can't see after fire forming being able to step up another grain of powder.

    Is it somewhat normal to see pressure signs this soon (low powder charge) in 80+ degree weather?
     
    Last edited: Jun 9, 2009
  6. KY Gun Geek

    KY Gun Geek Well-Known Member

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    Don't shoot a 270, so no direct experience. However, I have been working on a 338 since March and had a similar situation - sticky bolt on a warm day (though I haven't tried the cooler yet).

    I know I'm on the ragged edge - I bumped the charge until I got a sticky bolt (and loose primers) then backed off a grain. Weather got hot and I got some bolt issues again.

    Backed off another 1/2 and have no problems.

    No, I won't post the load, there's a good chance your rifle won't handle it. I will tell you I'm pushing a 225 gn Accubond about 2990. Powder is H4350 (an Extreme). But hey, I'm playing on the edge...
     
  7. JeffVN

    JeffVN Well-Known Member

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    I go not believe your experience is unusual.

    From living in Houston and doing reloading and load development (40 degrees in the winter and 90+ in the summer) and the same in Las vegas (40 degrees in the winter and 110+ in the summer), the key is muzzle velocity at the time you developed the load. You can down load during the summer to find the same velocity node.

    My brother and I have done so with some level of sucess with his .308 (it took only 0.3 of a grain of RL-15 to put him back in the node), and my 7wsm (0.5 of a grain with H1000).

    Jeffvn
     
  8. Limbic

    Limbic Well-Known Member

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    Happens to me all the time. When I work up a load I usually try and find one that is below max but still gives good velocity. This allows some stability. I also find that the humidity affects the MV a great deal. By great deal I mean up to 100fps. That may be something as well.

    My 168 Berger load is 70g of Retumbo. When it gets warm out I start to see plunger marks on the headstamp. WHen it is cool i'm good to go.
     
  9. Michael Eichele

    Michael Eichele Well-Known Member

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    I have found that if you run a MAX load that was developed in cool air and 80+ degrees comes around, pressure signs are sure to follow. It doesnt matter if it is "extreme" powder or not.

    The difference is when using extreme powders and you work up to max and actually back off, things typically stay cool even in warmer air. They key is IF you back down from max. Other powders may be more sensitive and show signs of high pressure in warmer air than when developed even under max loads.

    The bottom line is that if youre running absolute max loads that were developed in cool air, be prepared for pressure signs in the heat regardless of what powder youre using.
     
  10. jmason

    jmason Well-Known Member

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    I understand and expected that. I also understand no powder is impervious to temp. I just listed the powder type cause if I didn't someone would have asked. what surprised me is not being able to get within 100 fps or a grain of powder of "listed" max when working up in the hot weather. I have never been able to produce super fast loads in this gun (it just won't tolerate it) but have always been able to get a little closer than this.
     
  11. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Your rifle may like a different powder for the 130's than the 140's. Why not back off your load for the 140's a grain or two for the summer shooting, and when hunting season comes around go back to your cool weather load?

    Just a thought,

    Steve