Seating deeper to reduce pressure

Discussion in 'Reloading' started by Jinx, May 16, 2008.

  1. Jinx

    Jinx Well-Known Member

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    I only started hand loading. I have a 264 Win Mag Sako Finnbear. I loaded 129 grain Sierra tips. After the first shot my bolt was sticky to open. The gunsmith I use said I should seat the tips 1 millimeter deeper, it will help lesson the pressure. Is this true or not? Should I take out all the tips and reduce the loads?
     
  2. Varmint Hunter

    Varmint Hunter Well-Known Member

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    I would disagree with your gunsmith, primarily because there doesn't seem to be any reason to suspect that is the problem. The FIRST thing I would check is the powder charge. You shoud be starting with loads that are 15% below maximum or just use the lighter charges listed in a reloading manual. You may also want to confirm that you are using the EXACT same powder as is indicated in whatever source that you used. I might add that you should NEVER use unconfirmed loads that are listed on ANY web site.

    There could be other possible causes of excessive pressure like cases that are too long, wrong primers, etc but I'd look at the powder charge first and then look at less likely causes. Arbitrarily seating bullets deeper into a case could actually cause pressure to climb, however, 1 millimeter shouldn't make that much difference. If bullets are loaded to the length that is indicated in the appropiate manual then you should be fine when using a factory barrel or SAMMI chamber.
     

  3. .280Rem

    .280Rem Well-Known Member

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    There's little info to go on there, but on the face either your smith may be a competent smith, but not a competent hand loader, or you misunderstood what he said. In any event, like said above, if you seated it to SAAMI OAL, then, I'd look elsewhere for the cause of the problem. Seating deeper in the case can raise pressure. Seating further out, has been shown to have little effect on lowering pressure, but can a little bit. Think of it this way...seating deeper decreases case capacity/increases pressure. Seating further out increases case capacity/decreases pressure. I don't hold to the 15% thing on starting loads. In my opinion, 10% should be plenty off of max to start safe in a case like your loading for. Go back, check all your components, load data, COAL, and restart the load. If you're loading well under max loads, and your measurements are right, then it could be a gun problem, like headspace for instance. Eliminate the loading, and your procedures first.

    By the way, what is the load you're using?
     
  4. jwp475

    jwp475 Well-Known Member

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    If you are seating into the lands, then seating a little deeper can indeed lower pressure..
     
  5. eddybo

    eddybo Well-Known Member

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    Agreed, but unless that load is well below max and seated into the lands I would pull the bullets and try a lower charge.

     
  6. britz

    britz Well-Known Member

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    I agree w/ Edd and JWP in saying that seating to the lands can and will raise pressure. Allowing the bullet a "jump start" prior to hitting the lands can possibly reduce the pressure. HOWEVER!!! you shouldn't ever start loading with a hot charge. If you are already at minimum charge than think about seating deeper, but if not, pull the bullets and lower the charge. The best thing you can do is to purchase a good reloading manual and read the reloading procedures several times until you can recite and explain them to a novice yourself. We could use a little more information to help you farther such as case prep steps, primers, powder distance from the lands...
     
  7. boomtube

    boomtube Well-Known Member

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    You have told us what cartridge and bullet you are shooting but not what powder and charge you put under it. That data would help a lot.
     
  8. sjadventures

    sjadventures Well-Known Member

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    A sticky bolt alone may or may not be a sign of a pressure issue. Do you know for a fact that the cases didn't make the bolt sticky before you reloaded them? An improperly set resizing die can also cause a sticky bolt before even shooting the cartridge (learned this from personal experiance). If you have no other pressure signs it may be something other than over pressure. Do yo have any of the other high pressure signs? As far as where to start from Max when working up a load Bill Hober from Swift Bullet Co. told me personally that he and Swift recommended only dropping back 3gr from max to start working up a load. I used to go back to 10% but I only go back 3gr from max now and it saves a lot of time, powder and bullets when trying to work up a load.
     
  9. .280Rem

    .280Rem Well-Known Member

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    True. I didn't think of that because he didn't mention it...good thing you did.