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Reaming and Turning Necks

victorj19victorj19 Member Posts: 3,642 ✭✭✭
When should a neck be turned?

When should a neck be reamed?

I am getting ready to form some cases both up and down.


  • cbyerlycbyerly Member Posts: 689 ✭✭
    edited November -1
    When your expander ball has abnormal resistance coming out of the neck, it is time to inside ream. I usually anneal before sizing. Neck turning is a useless operation and destroys the life of the case.
  • navc130navc130 Member Posts: 1,161 ✭✭✭
    edited November -1
    The outside diameter of a loaded case neck is a critical measurement. The neck MUST have enough room to expand and release the bullet. If not, dangerous pressures can develop. In reloading, there are various reasons for a case neck to be reamed or outside turned. Reloading manuals are your best source of information.
  • nononsensenononsense Member Posts: 10,931 ✭✭✭✭
    edited November -1

    quote:When should a neck be turned?

    If the neck thickness varies enough to affect accuracy through a lack of concentricity. When you need to gain every tiny bit of accuracy potential from a cartridge. This generally does not apply to hunting since rarely does that degree of accuracy come into play, although it can.

    quote:When should a neck be reamed?

    Only to remove a donut which has formed at the inside neck and shoulder junction after fireforming.


    quote:Neck turning is a useless operation and destroys the life of the case.

    I'm not sure where you stumbled onto this piece of information but it is totally inaccurate.

    Whether shooting Short Range Benchrest, F-Class or Long Range Range Benchrest, we all turn necks of cases at some point in time or another. We learned this from the Short Range fellas when they started measuring the thickness of necks around each case neck and found variations. These variations are turned off in order to get the case into concentricity with the chamber and bore.

    As to 'destroys the life of the case', I and thousands of other accuracy minded shooters have cases on which we have turned the necks which now exceed 30 reloads per case. So much for that theory![:D]

    The one and only time I use an inside neck reamer is to remove the donut which often occurs when necking down one case to create another caliber case, after fireforming.

  • 243winxb243winxb Member Posts: 264 ✭✭
    edited November -1
    As said, ream to remove the donut that forms at the neck/shoulder junction, if there is to much to remove by outside neck turning. Doesn't hurt to outside turn 2 times if needed.

    Leave enough neck wall thickness after reaming, so the final cut is made by outside neck turning. The expander will push the excess brass, in the neck, to the outside for turning.
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  • best defensebest defense Member Posts: 30 ✭✭
    edited November -1
    quote:Originally posted by victorj19
    When should a neck be turned?

    When should a neck be reamed?

    I am getting ready to form some cases both up and down.

    I started shooting 600 yard matches about 4 years ago and this is what I found:
    After reloading any particular piece of brass a few times it starts to change. The change is usually in the fact that the material that the brass is made of starts to get displaced from the body of the case into the neck of the case. This situation causes two things that can be seen and or measured. First the material at the neck starts to get longer, and the thickness of the case walls at the neck will get thicker on one side than on another side. The case may also develop what is commonly called a doughnut inside where the shoulder starts up into the neck of the case.
    If you use a case neck turner that has a cutting pilot goes inside the neck while the outside blade cuts the outside diameter, you will eliminate both the doughnut at the same time you are truing the outside diameter of the case. This procedure does nothing for the length of the neck which is a separate operation.
    You did not ask about turning the case length.

    If you are using new cases to create some kind of wildcat cartridge all of this goes out the window, and you will need to fire form the case first unless the case is too long to fit into the chamber. That would be a case of cutting the length back.
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