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Thread: BUSHING DIES: have I understood the workflow correctly

  1. #1

    BUSHING DIES: have I understood the workflow correctly

    I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
    This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

    "The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."

    Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?

    Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?

    Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

    Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.

  2. #2
    Quote Originally Posted by tikkathreebarrels View Post
    I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
    This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

    "The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."

    Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?

    this is true,I remove my pin as I prefer to remove the primer using a different die

    Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?
    in my experience of using these dies for many years measure the wall thickness of your cases get the average the double it and add the bullet dia then subtract 2 thou



    Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

    Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.

    yes it will be repeatable on all your brass once you have found the most suitable bushing size,

  3. #3
    This is an interesting article relating to your questions and worth a read.

    http://riflemansjournal.blogspot.co....k-tension.html

    At present I don't use the expander ball when using a bushing die, however as in many of these questions, there are different opinions on what's best. I've ended up with a set of about a dozen different bushings in order to deal with different brands of brass and different chamber sizes.

    I use a decapping die to deprime the cases, then clean them, then resize and trim, before a final clean.

    Regards

    ​JCS

  4. #4
    Is the idea behind removing the decap ping pin from the size die to reduce working the neck or to improve concentricity?

  5. #5
    Distinguished Member Ronin's Avatar
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    Decap rod only does that - no re working of the brass internally.

    Selecting bushing for a factory chamber measure the diameter of fired brass.

    This will give you an indication of how large the chamber is (at the neck)

    Measure the inside diameter of the brass too

    You can then work out what bushing to buy

    Example - Factory 308

    Fired brass at neck measures .343"

    Inside neck Diameter (fired) - .310"

    Bullet dimeter - .308"

    So to get a slip fit - i.e.; zero neck tension, you would need to resize the brass .002"

    To get .002" tension you would need to resize the brass .004"

    Therefore using the original outside diameter of the fired brass (.343") and take away .004" will give a bushing diameter of .339" to give .002" neck tension on resized brass.

    This method works for me in factory chambered rifles, where I use bushing dies, it wont overwork the brass or create an unsightly and heavily swaged case neck around the seated bullet (as one sees in some factory die sets)


    Hope that helps

  6. #6
    Distinguished Member Ronin's Avatar
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    Simon,

    ​Yes,

    easier to have separate decap die and remove the internal mandrel on the die - its not necessary and overworks the brass

  7. #7
    Quote Originally Posted by jcampbellsmith View Post
    This is an interesting article relating to your questions and worth a read.

    http://riflemansjournal.blogspot.co....k-tension.html

    At present I don't use the expander ball when using a bushing die, however as in many of these questions, there are different opinions on what's best. I've ended up with a set of about a dozen different bushings in order to deal with different brands of brass and different chamber sizes.

    I use a decapping die to deprime the cases, then clean them, then resize and trim, before a final clean.

    Regards

    ​JCS
    Thanks for the link: I'll have a good read.

    Quote Originally Posted by Redmist View Post
    Decap rod only does that - no re working of the brass internally.

    Selecting bushing for a factory chamber measure the diameter of fired brass.

    This will give you an indication of how large the chamber is (at the neck)

    Measure the inside diameter of the brass too

    You can then work out what bushing to buy

    Example - Factory 308

    Fired brass at neck measures .343"

    Inside neck Diameter (fired) - .310"

    Bullet dimeter - .308"

    So to get a slip fit - i.e.; zero neck tension, you would need to resize the brass .002"

    To get .002" tension you would need to resize the brass .004"

    Therefore using the original outside diameter of the fired brass (.343") and take away .004" will give a bushing diameter of .339" to give .002" neck tension on resized brass.

    This method works for me in factory chambered rifles, where I use bushing dies, it wont overwork the brass or create an unsightly and heavily swaged case neck around the seated bullet (as one sees in some factory die sets)


    Hope that helps
    So bearing in mind that 7mm WSM isn't exactly on every RFD's shelves I need to knock up some "safe" unmeasured neck rounds, shoot 'em and then measure up for optimal bushing?

    Quote Originally Posted by see it shoot it View Post

    yes it will be repeatable on all your brass once you have found the most suitable bushing size,
    Suitable. Oh yes, that's what I'm looking for.

  8. #8
    Distinguished Member Ronin's Avatar
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    In essence yes

    I shoot a variety of 7 WSM's......

    Ive got numerous bushings too - let me know what size you work out, I may have it spare

    Ive also made my own bushings, thats an option if you cant find what you want off the shelf here, though they are available in 7-10 days from Sinclair international

  9. #9
    Quote Originally Posted by tikkathreebarrels View Post
    I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
    This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

    "The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."
    Individual results may vary. Redding stated 2 thou, then changed to 1.

    Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?
    Correct, serves no purpose. I think Redding bushing dies come with an expander ball and a decapping holder.

    Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?
    Measure loaded rounds and subtract from that. 1 thou is a starting point, I found 2 thou worked better in my .260.
    Also, brass thickness varies from manufacturer to manufacturer so expect to have to have a number of bushings when dealing with multiple makes.

    Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

    Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.
    Doesn't matter what tension you started with, the OD of the brass loaded is a function of the bullet and the neck wall thickness.
    Enjoy bushings... :-)

  10. #10
    Distinguished Member Ronin's Avatar
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    Theyre simple.



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