Throat length ?

Discussion in 'Gunsmithing' started by jsthntn247, Jan 28, 2013.

  1. jsthntn247

    jsthntn247 Well-Known Member

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    Would this measurement give me my throat length if I seat my bullets to just touch the lands. Measured base of case to ogive with a comparator ( ogive is just touching lands) 2.927. My cases measure 2.615 after trimming. 2.927-2.615 = .312. Is .312 my throat length. This should give me the length from the top of the case mouth to the lands since the ogive of my bullet is just touching the lands.
     
  2. J E Custom

    J E Custom Well-Known Member

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    It is possible but not very accurate.

    It would be best to buy a gauge that is designed to do this. (It would be more accurate).

    Seating bullets against the lands accuratly can be tricky.

    J E CUSTOM
     

  3. sj-pratt

    sj-pratt Official LRH Sponsor

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    To many unknown factors, it will get you close but not really, for one, the clearence between where your brass neck ends verses how deep the neck was cut in the chamber. But knowing the exact freebore is for why, if the bullet has plenty of neck depth and its touching the land or where ever you want it, the freebore is about right. Unless your trying to order another reamer and you need to tell the manufacturer what freebore you want so it matches your current chamber. What is the reason your trying to fiquire your exact throat length?

    Best of Luck
     
  4. jsthntn247

    jsthntn247 Well-Known Member

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    I am having the gun rebarreled, the gunsmith says his reamer has a 0 throat. I am assuming 0 throat means the reamer is to exact Sammi specs. 2.927 is as far as I can seat the bullets out and it to still function through the mag box. It also leaves enough room in the case for the slower powder that I want to use. I made two dummy rounds with the bullets seated at my desired length and will ship them with the rifle.
     
  5. sj-pratt

    sj-pratt Official LRH Sponsor

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    That is correct your smith will cut the throat after he is done with the chamber. I like the dummy rounds to be unfired just to make sure there is no resistence sliding them in that new tight chamber because they are the guage to measure the throat. You would be suprised how many times a fired round won't go in the new chamber.

    Looks like your on the right path enjoy
     
  6. Hired Gun

    Hired Gun Well-Known Member

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    Zero throat is not saami. It is a no throat reamer meaning no throat at all. It will require the use of a throat cutter to get any throat at all.
     
  7. sj-pratt

    sj-pratt Official LRH Sponsor

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    Good catch Hired Gun I breezed right over him stating sammi specs, there is surely nothing sammi about no throat.
     
  8. J E Custom

    J E Custom Well-Known Member

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    +1

    I do not recomend using a throating reamer unless you cant get one with SAMME dimensions
    and you want something different.

    Or have a reamer ground with the throat you want. (one reamer is always better than using
    two different reamers to do the job.

    I am not saying that a good job cant be done but I feel one reamer is better.(More concentric).

    Some smiths buy there reamers with zero throat so they can throat to any dimension the customer
    wants and it saves reamer cost. I like to have a reamer ground for the chamber desired. this way
    it can be used again on the same barrel to clean up the throat and the chamber after hard use with
    little change in the loads that were used before.

    I have had to throat chambers that had zero throat because of pressure problems and I
    prefer to use a chamber reamer to throat and clean up the chamber at the same time.
    set the shoulder back, and head space for a good job.

    This is just my preference.

    J E CUSTOM