Whats the Proper Way to Measure a Reamers Freebore?

Discussion in 'Gunsmithing' started by Broz, May 2, 2013.

  1. Broz

    Broz Well-Known Member

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    OK, so I have a rifle and want the next one I build to have a little more free-bore. I have a measurement from the case head to the O-give (where the bullet touches the lands) but no reamer specs to know what the current reamer had for free-bore. How do I get a measurement on the current rifle's free-bore so I know what to order for the next reamers free-bore?

    Thanks
    Jeff
     
  2. J E Custom

    J E Custom Well-Known Member

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    In your case, I would make a chamber cast of your chamber using Cerrosafe because it will show
    everything even the condition of the lead. Cost about $20.00 bucks.

    Once you make a casting of your chamber it is easy to measure any part of the casting. Just
    be sure to follow the instructions TO THE LETTER.

    It is very hard to measure a reamer and you must be careful what you measure it with because
    most Micrometers anvils are very hard and can damage a fine reamer.

    Have you have tried the maker to see is he has the reamer print for it ?

    PS: If the barrel and chamber are good you can buy a throating reamer and do what ever to the
    free bore you want. In fact this is a good way to experiment with throat/free bore length using
    the old barrel before you re_barrel with a new barrel

    I hope this helps

    J E CUSTOM
     

  3. Broz

    Broz Well-Known Member

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    My rifle I have now I ain't doing anything too. It is great, but I am building a new rifle and want to add just a little free-bore. I can't get specs on the reamer used on my rifle so I don't know what to look for or order for a free-bore spec. I can guess that my rifle was done with a PT&G "Tactical Match" reamer, says on barrel (300 win Tactical Match) but it is only a guess. I know where the O-give was in my rifle when new, I have all that documented. Just don't know what a reamer maker would call it for free-bore. ??

    Thanks
    Jeff
     
  4. IdahoCTD

    IdahoCTD Well-Known Member

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    Jeff,

    You can send in a dummy case with how you want it rather than specifying a numerical length. That way they can measure it for their purposes. I've done that numerous times.

    Nathan
     
  5. Broz

    Broz Well-Known Member

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    Thanks Nathan, Yes I have done this too. I was just wanting to learn how they come up with their "free bore" measurements. Then I could know what "in stock" reamers will work when and if I do find one in stock. Right now the wait times for a custom grind are unbearable.

    jeff