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Brass length shortened after necking down?

Gregor.Samsa

Gunny Sergeant
Full Member
Minuteman
  • May 4, 2019
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    777
    NorCal
    I just FL sized once fired 6.5CM Peterson brass in a 6CM due to neck it down. The brass was annealed before sizing and then mandrel expanded afterwards. I did not measure the brass lengthy prior to doing any of this, I assumed it would need to be trimmed. I just measured the cartridges and they are measuring between 1.905”-1.907”. Book trim length is 1.910”. Is this usually the case (no pun intended lol)? Is this brass still ok to be used? Thanks
     
    Hard to tell without knowing what it was before. I wouldnt be concerned with coal as it basically means nothing so long as its not too long.
    I would make sure your cases have adequate diameter clearance in the chamber. Sizing it down makes em thicker.
     
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    You said yourself you dont know if they have shortened.
    this is true! I really should have measured first and made the assumption that the cases were longer. I cant see them being shorter than trim length though after one firing.
     
    Once fired Peterson brass, I am pretty sure it did not shorten on you, mic one of the other cases as 6.5 CM and check the length. All my Peterson started out a few tenths short and took a few firings to lengthen.
     
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