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Question For Guys That Use Neck Bushing Dies?

Steel+Killer

Killing one steel plate at a time!
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  • May 27, 2014
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    Question for you guys that use neck bushing dies to get the exact neck tension you want. I just bought some new RCBS 6.5CM Match Master dies that come with the sizer die that uses neck bushings I also bought a pretty good range of bushings using the recommended method. My question when using the neck bushing die do you still use the decap rod assembly with Expander Ball/Decap Pin Holder? I am thinking no correct? Also kind of a secondary question is why do regular sizing dies over size the neck requiring the use of the expander ball in the first place?
     
    You can use it. Many use a mandrel instead. The problem with using no ball or mandrel is your neck ID won’t be round due to neck wall variances. The ball or mandrel use pushes the defects to the outside.
     
    You can use it. Many use a mandrel instead. The problem with using no ball or mandrel is your neck ID won’t be round due to neck wall variances. The ball or mandrel use pushes the defects to the outside.
    but wouldn't using an expander ball or mandrel then determine/set the neck tension? At that point it wouldn't matter what size neck bushing you used man I am confused....LOL
     
    but wouldn't using an expander ball or mandrel then determine/set the neck tension? At that point it wouldn't matter what size neck bushing you used man I am confused....LOL

    Depends what bushing you use...if you squeeze the neck down more with a smaller bushing the expander won't open it back up as much as if you used a larger bushing......you need to test different
    bushings to find the combo that gives you the final neck tension you desire...

    I remove all buttons from all my dies.....size down to .004 under final neck diameter and open up .002 with a mandrel to give .002 final neck tension...
     
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    but wouldn't using an expander ball or mandrel then determine/set the neck tension? At that point it wouldn't matter what size neck bushing you used man I am confused....LOL
    Mostly yes, but necks being springy you will see a differences if you change to a smaller bushing. You can also polish the expander ball down if you like. I’m usually satisfied with what the expander ball produces, and I choose the bushing so as to work the neck as little as possible. I don’t know what the design your decap rod/ball is as I’ve never used those dies, but I’m a big fan or Hornady match dies and their floating decap assembly, and short bearing surface expander balls. The don’t suffer from many of the bad features of many rod/ball designs like Redding’s.

    To your second question in your first post, the die maker has to choose the neck diameter to take all brass, thick or thin. So the diameters tend to be small. Most reloaders probably don’t get the brass life people like us expect.
     
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    Question for you guys that use neck bushing dies to get the exact neck tension you want. I just bought some new RCBS 6.5CM Match Master dies that come with the sizer die that uses neck bushings I also bought a pretty good range of bushings using the recommended method. My question when using the neck bushing die do you still use the decap rod assembly with Expander Ball/Decap Pin Holder? I am thinking no correct? Also kind of a secondary question is why do regular sizing dies over size the neck requiring the use of the expander ball in the first place?
    Typically bushing dies will come with a non expander ball rod end pin holder. I run the rod but with either the non expander ball rod end. On my Redding I just broke off the decap pin since it's a different set up. It's a straight rod without any kind of ball with a decap pin rod one piece.
    Typically sizing dies that aren't bushing dies size the neck to Saami minimum which is like 4k undersize. The sizing that goes on in that die is alot of squeeze which can cause the neck to kind of point inward. The expander ball takes it to a uniform straight wall as best it can.
    If you use a bushing die without any kind of neck dressing you will also want to mandrel since a bushing dies pushes any imperfections into the inside (neck tention) side of the neck.
     
    None of my dies have the expander mandrel in them. Why pull something back thru the neck that would change your head space. Possibly pulling it to the point it will not chamber. If your measuring your fired brass and setting your dies to bump the shoulder back .003 to .004 then pulling a expander back thru it you have just undone all your work for sizing. Another part to the puzzle is dwell time in your die. Running brass in and out with a quick press stroke will also have your brass all over the place. Allow it to normalize in the die, this will also show in consistent neck tension (Assuming you have neck turner your brass) and head space. Quick stroking the press handle leads to bad things.

    Why neck down past where you want to be then to just expand back. Brass Work hardens. The brass will form to the bullet as long as your Neck ID is smaller then the bullet OD, and walla your Neck is round to match the Bullet! Don't make things harder then they appear.

    My answer to you is to dump the expander. Neck wall thickness X2 plus your bullet diameter minus .003 to .005 depending on how much tension you want.
    Pick your bullet, primer, and powder charge, and tune it with your seating depth. Every load will shoot with the proper seating depth, even factory ammo.
     
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    None of my dies have the expander mandrel in them. Why pull something back thru the neck that would change your head space. Possibly pulling it to the point it will not chamber. If your measuring your fired brass and setting your dies to bump the shoulder back .003 to .004 then pulling a expander back thru it you have just undone all your work for sizing. Another part to the puzzle is dwell time in your die. Running brass in and out with a quick press stroke will also have your brass all over the place. Allow it to normalize in the die, this will also show in consistent neck tension (Assuming you have neck turner your brass) and head space. Quick stroking the press handle leads to bad things.

    Why neck down past where you want to be then to just expand back. Brass Work hardens. The brass will form to the bullet as long as your Neck ID is smaller then the bullet OD, and walla your Neck is round to match the Bullet! Don't make things harder then they appear.

    My answer to you is to dump the expander. Neck wall thickness X2 plus your bullet diameter minus .003 to .005 depending on how much tension you want.
    Pick your bullet, primer, and powder charge, and tune it with your seating depth. Every load will shoot with the proper seating depth, even factory ammo.
    This is part of what I mentioned earlier, most expander assemblies are garbage. If your expander assembly Is pulling out .003-.004 worth of shoulder, it’s extra extra garbage. My target is .001 headspace not .003-.004, and ive never pulled a shoulder out during the sizing operation that would prevent a sized case from chambering. If I did encounter that, I’d polish the expander. Let me guess, you’re using Redding dies? I own a ton of Redding, and all the expander balls are polished, which helps a lot. Still not as nice as a Hornady expander ball though.

    If the neck walls thickness varies, your ID will not be round without the use of a mandrel or ball. Brass does work harden as you noted, but I haven’t split a neck in a decade, and some of my brass is near 30 firings. I do anneal occasionally.
     
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    Why neck down past where you want to be then to just expand back.
    This was my thought as well seems to be the whole point in a neck bushing type die.

    This is from RCBS instructions.........
    Remove the Neck Bushing retainer and insert your selected diameter Neck Bushing. Neck Bushings must be installed so that you can read what is stamped on its side, do not install upside down (see photo 1, right). The Decap Rod assembly comes with an Expander Ball/Decap Pin Holder installed to allow for the proper preparation of a new lot of brass. The Decap Pin holder found in the accessory bag must replace the Expander Ball for proper use with the Neck Bushings (see photo 2 right). Reinstall your Neck Bushing Retainer. Do not tighten the Neck Bushing retainer down on the Neck Bushing, back it off slightly to allow the Neck Bushing to 'float' and center itself around the case neck.
     
    This was my thought as well seems to be the whole point in a neck bushing type die.

    This is from RCBS instructions.........
    If you were neck turning or had perfectly uniform necks to begin with, that would absolutely be the way to go. I’ve already mentioned neck wall variance around the circumference but Imagine uniform necks that vary in thickness from case to case .001. Not unusual at all. The thick neck run into a bushing would have a .001 more neck tension than the thin necks. You’re maximizing the error, and your velocity spreads will suck. If you push them all down, then drag them all over a ball (or mandrel), you minimize the error. Not only do I not want to neck turn, I don’t even want check to see where my necks are. Pick a bushing that causes all the cases to just kiss the expander ball and you’re done.
     
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    Yeah if you are using bushings and not doing anything to the necks either a polished expander or a mandrel, I would say is an absolute have to if you want any kind of consistency. Brass isn't going to work harden excessively when you are talking .5-1.5 thou here or there. And if you are rolling 5k neck tention good luck with all endeavors. That's terrible advise unless you are rocking a Scar or something and absolutely have to. Anything north of 3k neck tention is getting excessive.
    The most important thing you can do is have consistent neck tention whichever way you go about it.
     
    You guys have shed some light on neck sizing and neck tension, it almost seems like final neck sizing should be looked at from the inside out not from the outside in like it would make more sense to have different size expander balls or mandrels instead of different size bushings. With that said I don't see a lot of options in that regard.
     
    That’s where mandrels come in. Those would give you options for size, but also add second operation to your case sizing. I have the die and a set of mandrel for the common bore sizes, but I want simple. If I can make the expander ball work, I use it.
     
    I never really liked messing with bushing dies. I keep coming back to the Lee Collet die combined with a redding body die.
     
    I never really liked messing with bushing dies. I keep coming back to the Lee Collet die combined with a redding body die.
    It's a very good setup.
    You guys have shed some light on neck sizing and neck tension, it almost seems like final neck sizing should be looked at from the inside out not from the outside in like it would make more sense to have different size expander balls or mandrels instead of different size bushings. With that said I don't see a lot of options in that regard.
    You can get mandrels of any size. Might have to call Sinclair.
     
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