factory ackley Improved

Discussion in 'Gunsmithing' started by one crazy kid, May 29, 2014.

  1. one crazy kid

    one crazy kid Well-Known Member

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    I was wondering if was possible to rechamber a tikka t3 lite from 260 to a 260AI without replacing the barrel? If so is it even safe or practical?
     
  2. J E Custom

    J E Custom Well-Known Member

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    The Ackley Improved chamber reamers are designed to clean up the parent chamber if is it is tight and head spaced correctly.

    You just have to watch the headspace very closely to prevent having to set the shoulder back.

    I prefer to set the shoulder back one thread and then cut the AI chamber (This makes sure that the old chamber cleans up and I can set the correct head space. It also freshens the lead angle.

    And yes it is safe to re-chamber to a AI of the same cartridge.

    J E CUSTOM
     
  3. one crazy kid

    one crazy kid Well-Known Member

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    Thanks for the info, I have another question, if I got a SAAMI spec reamer would I still be able to run factory ammo through it? I plan on getting SAAMI spec brass anyway, I'm just fishin for info. I was also wondering about the mag? will it need any changes?
     
  4. shortgrass

    shortgrass Well-Known Member

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    SAAMI= Sporting Arms & Ammunition Manufactures Intitute Of course you can use 'factory' ammo in a SAAMI speced chamber. Both are manfactured to SAAMI specs,,,,, industry standards. Nothing "custom" about SAAMI specs. For proper head spacing, any conversion to "Ackley" will require the barrel to be set back.
     
  5. sable tireur

    sable tireur Well-Known Member

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    It is correct to set a barrel back one thread in order to achieve proper headspace when creating an Ackley chamber. However...

    The leade is a straight walled cylinder just ahead of the transition angle which is in front of the neck area in the chamber. The angle you refer to is the throat which is in front of the LEADE.

    Regards.
     
  6. J E Custom

    J E Custom Well-Known Member

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    Sorry to disagree but the leade is in front of the free bore (The free bore is the bore diameter of the bore + .0003 to .0004)and is the transition between the bore diameter and the rifling diameter( It is normally 1 to 2 degree's)

    J E CUSTOM
     
  7. sable tireur

    sable tireur Well-Known Member

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    J E Custom,

    There is no reason to apologize for disagreeing. That's how many questions get resolved in the long run. I realize that the forum regulars often view new members with low post counts as lacking experience and knowledge, which in this situation is a mis-characterization. After advanced work in physics and ballistics and 30 years in gunsmithing designing and custom building rifles, it is not unusual for me to still find some folks who seem to have this nomenclature thing a little backward.

    The information as you relate it to this question is incorrect. Please take a look at the PTG reamer print below and notice where the term 'LEAD' (LEADE really) is placed. Then take a look at where the area is marked 'Throat'.

    It is the throat which has the angle since this is the area of the chamber where the bullet is funneled into the bore/grooves of the barrel. The angle can vary from a little less than 1 degree up to about 3 degree.

    The LEADE is the straight walled, cylindrical portion of the chamber which is found right in front of that 45 degree angle referred to as the transition angle for a good reason. It reduces the size of the chamber down from the neck diameter to the LEADE diameter. The LEADE is approximately 0.0005" larger in diameter than the bullet.

    This misunderstanding can often be traced to discussions involving Weatherby cartridges where the term 'free bore' was substituted for the correct term, LEADE.


    [​IMG]
     
  8. J E Custom

    J E Custom Well-Known Member

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    First, let me clear up something, I cant speak for the other posters but I don't think that the number of post I have posted makes me any smarter. The number I read does. I learn lots from the new members and respect there opinions and knowledge.

    I found a good description of everything for the rest of the members to look at and It appears that we both may be right.

    The Rifleman's Journal: Basics: The Leade Angle

    You have to read the whole article to understand it (And it is still a little confusing Because they use the term lead angle in conjunction with the Leade/free bore.

    It may be just semantics and the reamer makers know exactly what I want when I order a reamer with .xxx Free bore and a 1.5o lead angle.

    I will not try to explain or interpret any of this, that will be up to the reader to understand it the way they want to. I definitely under stand more now than I did.

    All modern High pressure cartridges have free bore to keep the pressures down and the velocities up and is a now common
    term.

    The main thing is for everyone to understand the purpose of each element of the chamber and its effect on performance
    be it accuracy or velocity

    Thanks

    J E CUSTOM
     
  9. sable tireur

    sable tireur Well-Known Member

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    Out of town work and competition has kept me away for a bit.

    Germán A. Salazar is a very nice man, a good shooter and a lawyer who just happens to write a blog. I have shot with him on squads in Phoenix although I'm sure he won't remember me. Simply writing a blog does not make anyone an expert which might be the contributing factor to some of the confusion. Don't misunderstand, the internet is a marvelous place to read and be entertained. Sometimes it's even a good platform for learning as long as the writer is qualified. But many times there is information which is incorrect and needs to be corrected or at least explained more thoroughly. Prevalent misuse of some terms is not a reason or excuse to continue using the wrong terms nor does it make the wrong terms right.

    A perfect example is the misuse of the term 'clip' instead of the proper term 'magazine' in context when referring to DBM. Or even more mundane, the corporate product name 'Kleenex' used as a generic description for every facial tissue on the market. We all do that, I'm pretty sure... Or the exact differences between the .223 Remington cartridge and the 5.56 NATO cartridge. Or even more pervasive, using the term 'CALIBER' when the proper term should be 'CARTRIDGE'. The two are NOT interchangeable, they are mutually exclusive by definition.

    Now be that as it may, the terms LEADE and THROAT as I laid them out are still the industry standard, proper terms and use. If folks decide to use something other than these terms in another type of description, that's up to them. Those of us who function in the daily technical aspects of gunsmithing design, production and teaching will continue to use the terms as I stated above. I was merely trying to add a little bit of information to the general knowledge base.