I think my chamber is undersized HELP!!

Discussion in 'Reloading' started by Tony 0321, Dec 10, 2009.

  1. Tony 0321

    Tony 0321 Active Member

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    I just got my first long range rifle back from the gunsmith after a couple month wait well I am having problems with the shells fitting in the chamber..
    I can load a new unfired round in the chamber but the problem I am having is that I have a few rounds left over before the rebuild and some cleaned resized cases I was going to use for the break in.. Just behind the shoulders the mesurement of new unfired brass is .521 and I can chamber this in my rifle with no problem . However when I try to use the brass that I have that has been resized it dosnt fit acording the the nosler book that I use for reference the mesurement just behind the shoulders is suposd to measure .525 and all of my rounds measure that exactly..I used a candle to put sut on the brass to see where it is rubbing at and it seems that the brass needs to actually be smaller than what the specs are for it

    My question is.. Is this a problem or can I get shims or a different resizer to push it down so they will fit or was my chamber cut wrong. Can I reuse my old brass or do I need to just use a neck sizer and fireform new brass.. any input would be grealy appreciated..

    Oh yea this is a 300 rum, kreiger 26in barrel hs precision stock built on a remington 700 action
     
  2. Moman

    Moman Well-Known Member

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    Have you measured the brass on the datum line? It sounds like your shoulders aren't getting pushed back far enough. I am rebarreling a gun and bought new brass for it. I talked to a few gunsmiths and when the topic came up, they said to buy new brass. Hope this helps.
     
  3. Tony 0321

    Tony 0321 Active Member

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    Its not that the shoulders are not being pushed back far enough I cant even get the round in the chamber far enough for that to be an issue I used a candle to put sut on the brass and the area that is too big to fit into the chamber is the area just imediatly behind the shoulders.. The brass seems to be .002 to .003 too wide after a full resizing from my old rifle but the specs are right on acording to my reloading book
     
  4. Moman

    Moman Well-Known Member

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    Tony, I remember reading a post similiar to this in that the reamer was a minimum spec. The problem was similiar but they were having issues with stuck cases after firing. I'll paste the link below, check out page 4, this will explain the problem once it was discovered. You may also want to post this in the gunsmithing section.

    300rum-reloading-experts-needed
     
  5. Moman

    Moman Well-Known Member

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  6. Winchester 69

    Winchester 69 Well-Known Member

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    Factory chambers are generous, and standard dies are sized to work with them. Redding makes a series of small-based dies that are made to the minimum of SAAMI spec. You may want to consult with your gunsmith, and then ask Redding if their die will meet your needs.
     
  7. Tony 0321

    Tony 0321 Active Member

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    Thanks Moman this sounds like the exact problem that I cant even get a round into this chamber that has been reloaded..
    I just went out and mic out the brass that was test fired through this rifle and compared it to a resized case that was already fired from my old 300RUM and I am really stumped now according to all my measurements it should fit but dosnt .. the resized case is at least .001 less everywhere but wont fit..
    This sounds really dumb but I dont know what is happening.. I am going to try to just use new brass and reload them to see what happens.. Thanks for your help I am going to have to get back with you guys after I do some more looking at this and some more test firings.
    A full length resized casing should fit any 300RUM right???
     
  8. Tony 0321

    Tony 0321 Active Member

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    Thanks for that info I am scratching my head on this one.....
    But this is what makes all this fun if it was easy half of us wouldnt even think of doing it ourselves
     
  9. mo

    mo Well-Known Member

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    I would think new brass will solve your problem. I had same problem with a 284 winchester that were fired in another one of my rifles. I bought new brass, and everything was fine.
     
  10. esshup

    esshup Well-Known Member

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    I've got 2 factory Wby .257's. One Vanguard and one MarkV. I ended up buying different headstamped brass for each rifle because the MarkV needed to be resized much smaller than the brass for the Vanguard. My problem was solved once I bought new brass and I just have to remember to adjust the full length sizing die for each gun.
     
  11. justgoto

    justgoto Well-Known Member

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    I load for 3, 30-06s and use new brass and keep the brass separate for each.