Tight Chamber

Discussion in 'Gunsmithing' started by baldhunter, Sep 24, 2012.

  1. baldhunter

    baldhunter Well-Known Member

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    I picked up a 7mag recently in a trade.It has a supposedly a Douglas stainless barrel.I'm fairly certain the barrel never had a round fired through it,if it did ,someone did a darn good job cleaning it.When I chamber a round,I get a lite smear on my head stamp.I readjusted my full length RCBS die down an extra 1/4 turn and it seemed to help a little,but it's still a snug fit.I took the rifle out and fired a dozen test loads through it and it shot very well and I had no problems opening the bolt.I full length sized some of the brass I shot through it.The brass seemed to chamber a little easier,but it already had the lite headstamp smear.What can I do for this?

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  2. barnesuser28

    barnesuser28 Well-Known Member

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    Im curious as to what your problem is, as this is happening with my 338 Lapua. Sorry i dont have any knowledge to contribute.
     

  3. baldhunter

    baldhunter Well-Known Member

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    I just got a new to me older RCBS die set.Set the die up the same way as my other die was set,now the problem is gone.Brass chambers with no problem.I never had any problems with my other 7mag using the other die set,just this rifle.
     
  4. Bullet bumper

    Bullet bumper Well-Known Member

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    If it chambers with some resistance and then you screwed the die 1/4 turn more that is and increase of .0178 . That should be way too much only you do have a belt to save you .
    I think the die is not matched very well to the chamber or the sizing die is not getting all the way to the belt . Mike up the case and see if there is a bulge just ahead of the belt. If yes then get the belted magnum collet die Innovative Technologies - Reloading Equipment
     
  5. baldhunter

    baldhunter Well-Known Member

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    I set the newly acquired die at 1/4 turn as per directions from RCBS and the brass chambers perfectly.I rechecked my older RCBS die and reset it at a 1/4 turn,resized some brass and it has very lite resistance when resizing the once fired brass.The newly acquired die has noticeably more resistance when resizing the brass even when resizing the brass that was previously run through the older die.The chamber may be tighter on this rifle than my other 7mag,but there definitely is a noticeable difference between the two dies.
     
  6. Bullet bumper

    Bullet bumper Well-Known Member

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    With Magnums that head space on the belt it does not matter much as far as safety goes if you push the shoulder back a bit as it just blows forward again .
    As far as accuracy goes it is better to have minmum blow forward . However one die could be getting closer to the belt than the other or one die is a better match to the chamber diameter or taper than the other . Clean the chamber and leave it dry of any oil . Take a tight case and polish it up with fine steel wool really shinny and then chamber it a few times . Then inspect the surfaces for chambering marks . That may give you an idea of where it is tight .
    Marker pen can work also.
    Don't forget to re-oil the chamber and bore after .
     
  7. baldhunter

    baldhunter Well-Known Member

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    OK,I shined up a case sized with each die.The older die shows two faint rings around the slope of the shoulder and a tool mark about 1/32 x 1/8 inch down the slope of the shoulder that was most likely caused by the reamer.The newly acquired die appears to be bumping the shoulder back just enough that the two rings around the shoulder are gone but the tool mark is still present.The tool mark does not seem to affect anything,but I was definitely getting too tight of a fit with my older die set.
     
  8. Bullet bumper

    Bullet bumper Well-Known Member

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    Is the tool mark in the die or the guns chamber ?
    Now try a tight unsized and polished case in the guns chamber and see where it is tight in the chamber . Compare that to the cases run through the dies.
    Might give you an idea of where it is sticking in the chamber and if the dies are missing that spot.
     
  9. baldhunter

    baldhunter Well-Known Member

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    Yes the tool mark is in the chamber because it appears on the case using either die.The case run through the older die showed rings from the chamber on the shoulder.Shined up the case again,then the same case was run through the newly acquired die,those rings on the shoulder disappeared,but the tool mark was still there.