Need guidance...case neck thickness

[bigedp51]

Which is a great reason to turn necks then throw the expander away. Once irregularities are pushed outside, then accuracy suffers because the projectile path into the throat varies depending on how that case is indexed inside the chamber. In other words, with the high spot at 11:00, it will shoot a little different when that case is indexed in the chamber at 7:00 or 5:00. (Love the Avatar!)

In a factory rifle the chambers neck is large enough in diameter that neck irregularities do not have any effect on bullet alignment in the throat.

And the Redding bushing die FAQ tells you if the neck thickness varies .002 or more to use the expander that comes with the bushing die.

 

[DUSTY NOGGIN]

In a factory rifle the chambers neck is large enough in diameter that neck irregularities do not have any effect on bullet alignment in the throat

i think that drawing shows how a turned once fired would fit .. not an un-turned case seated with run out , there is slight clearance at throat not in illustration (slight 1/2 thou) , plus you would also have a gap at the shoulder junction as big as the run out is , causing contact at opposite side of shoulder causing a tight close ( if sized to the 002 most suggest )

 

[bigedp51]

Below is a bad case of runout in a factory chamber and the case neck was not touching the chamber. And a custom rifle with a tight neck chamber would have far less neck clearance.

Bottom line, bushing dies work best in custom tight neck chambers where the bushing does not reduce the neck diameter that much. And in a factory chamber neck turning allows the neck to expand more when fired. And the Redding bushing FAQ tells you that reducing the neck diameter .004 or more can induce neck runout. And a full length Forster die with a honed neck would be a better choice.

 

[DUSTY NOGGIN]

i do not turn for neck clearance , i turn for brass neck runout repair upon next firing

im guessing the pictured brass was full length sized . in which you would expect to see those marks

bushing dies may be needed in tight neck chambers , but they also work great if you have a snug fit in the shoulder cone (you should see ink disruption)
i will try an ink on of mine when i get a minute -- i think you will see touch rings on shoulder and very little marks on bullet , besides extraction drags -- but i may need to size some once fired before i can do that

i don't think you will find anyone recommending turning off .004 .... Most of the time turning .002 to .0025 ( overall circumference) will turn true any case

 

[DUSTY NOGGIN]

would add, sometimes it possible to turn true down neck to match a basic FL sizing to get better tension & just to loosen up the excessive squeezing a standard full length sizing die does ,, no expensive bushing dies needed .. that is a perfect scenario for those honed die sets you linked

 

[birdiemc]

IF you had a tight neck, you would cut all the way around so that the loaded round would have about .0015" RADIAL clearance or .003" total clearance. (For example, a .262 6mm neck chamber needs the brass to be cut to about .008" thickness. .264 + .008 + .008 = .259").

I have read this over and over trying to figure out the math there and it doesn't make sense to me. Was that a typo? Supposed to be .243+.008+.008=.259mmm cuz that makes sense, 6mm bullet plus two case wall thickness to get you .003 below internal chamber dimension. Is that what was meant? I've been scratching my head for days trying to figure out what I'm missing here

 

[woods]

It is also possible to take your FL die and remove the expander, then turn the necks down to give you the bullet grip you want

Example: (I don't have any FL dies anymore so operating from memory)

Loaded for a friend's 300 Wtby and in order to use his FL die I removed the expander and IIRC the outside diameter of the neck AFTER SIZING sans expander was .332". So if I turned the necks down to .013" then I could get .002" bullet grip

.332"-.306" (which is caliber minus .002") = .026" / 2 = .013"

Essentially you are making your FL die do the work of a bushing die and regulating by neck thickness for bullet grip

Doesn't work for all chambers and dies

 

[birdiemc]

Woods,
From what I've read about the process and applying a little (perhaps misguided) logic, it seems when you cram the case into the FL size it compresses the brass i.e. closing up the case mouth, which results in stretching I think, then when you yank it back out the expander pushes it out radially opening the case mouth back up... but some folks claim that process presses any "irregularities" to the exterior surface of the brass which can easily be removed by turning. So if you remove the expander does that leave the "irregularities" on the inside and effect neck tension or runout?

 

[DUSTY NOGGIN]

It is also possible to take your FL die and remove the expander, then turn the necks down to give you the bullet grip you want

Example: (I don't have any FL dies anymore so operating from memory)

Loaded for a friend's 300 Wtby and in order to use his FL die I removed the expander and IIRC the outside diameter of the neck AFTER SIZING sans expander was .332". So if I turned the necks down to .013" then I could get .002" bullet grip

.332"-.306" (which is caliber minus .002") = .026" / 2 = .013"

Essentially you are making your FL die do the work of a bushing die and regulating by neck thickness for bullet grip

Doesn't work for all chambers and dies

i do this on 30/06 but leave the expander in. same idea .. because i dont really want to buy a spendy bushing die for it -- works great

thinner necks dont pull your shoulders up as likely , when pulling out the expander

 

[DUSTY NOGGIN]

I have read this over and over trying to figure out the math there and it doesn't make sense to me. Was that a typo? Supposed to be .243+.008+.008=.259mmm cuz that makes sense, 6mm bullet plus two case wall thickness to get you .003 below internal chamber dimension. Is that what was meant? I've been scratching my head for days trying to figure out what I'm missing here

good catch , he had to confuse the hell out of you so it would stick ,

 

[DUSTY NOGGIN]

Woods,
From what I've read about the process and applying a little (perhaps misguided) logic, it seems when you cram the case into the FL size it compresses the brass i.e. closing up the case mouth, which results in stretching I think, then when you yank it back out the expander pushes it out radially opening the case mouth back up... but some folks claim that process presses any "irregularities" to the exterior surface of the brass which can easily be removed by turning. So if you remove the expander does that leave the "irregularities" on the inside and effect neck tension or runout?

i think he said that as if he had previously prepped , manderal'd and turned the brass , so the high sides werent there to push inside

 

[woods]

Woods,
From what I've read about the process and applying a little (perhaps misguided) logic, it seems when you cram the case into the FL size it compresses the brass i.e. closing up the case mouth, which results in stretching I think, then when you yank it back out the expander pushes it out radially opening the case mouth back up... but some folks claim that process presses any "irregularities" to the exterior surface of the brass which can easily be removed by turning. So if you remove the expander does that leave the "irregularities" on the inside and effect neck tension or runout?

If you do a complete turn, IOW take off brass all the way around and not just hit the high spots, there are no more irregularities

Of course as with any process, it is hard to get a perfect turn. I would estimate that you can get the neck thickness to +-.0005", but that is small enough not to qualify for an irregularity, IMO

 

[birdiemc]

So Woods, is what Dusty said accurate, doing this on previously prepped and turned brass?

 

[woods]

Your question

So if you remove the expander does that leave the "irregularities" on the inside and effect neck tension or runout?

Dusty's answer to your question

i think he said that as if he had previously prepped , manderal'd and turned the brass , so the high sides werent there to push inside

is consistent with my answers.

Essentially I outside turn new cases and only have to do that once. Same for the FL die sans expander, turn new cases once

Now there is one time that I use the outside turner on once fired cases in conjunction with the reamer at the same time

but that is to get rid of a do-nut that forms on my 280AI brass and in order to use the reamer (reamers are .003" over caliber) I have to outside turn new brass in order to have the .003" clearance from neck expansion from fire forming. In that case I only skim the outside