Full length resizing question ( neck stretch )

M

moreguns

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What will give me the most uniform shoulder set-back / neck joint point. RCBS full-length sizer with Hornady carbide expander or redding full-length coated bushing ? How much difference between the two ? Well after I tested my RCBS /Hornady carbide expander set up with RCBS case lube II ( water salable) inside the neck it looks like that process will not pull the shoulder forward when full-length sizing,problem solved.
 
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I'm not sure that the expander does anything towards neck lengthening. That being said a bushing die will size the necks down only as much as needed and no more through proper bushing selection.

If your case necks aren't turned or otherwise sorted for uniformity of neck thickness then you'll need an expander. Redding's carbide expander floats on the decapping stem, and although I haven't done any measurements it would seem that this floating expander would have less tendency to tweak the case necks out of concentricity with the case body. That's the setup I use in my live varmint rifles, and the prairie dogs don't like it at all.

If your case necks ARE uniform in thickness ±0.0005" then you don't really need a neck expander, and should use a bushing die.
 
I turn my necks with RCBS neck turner that fits on their trimmer. With a auto feed it is quick .
 
moreguns said:
I turn my necks with RCBS neck turner that fits on their trimmer. With a auto feed it is quick .
Click to expand...

Have you measured the neck thickness uniformity with a tubing micrometer? I tried turning necks with the attachment Forster makes for their trimmer, and found that the results were somewhat less than satisfactory. Maybe I didn't do it right, but I've had no problems with either a Sinclair or K&M neck turner.
 
Larry Elliott said:
Have you measured the neck thickness uniformity with a tubing micrometer? I tried turning necks with the attachment Forster makes for their trimmer, and found that the results were somewhat less than satisfactory. Maybe I didn't do it right, but I've had no problems with either a Sinclair or K&M neck turner.
Click to expand...
Within .001" overall for uniformity, as long as I expand properly.
 
Good case necks should be within 0.001" without turning. If you're using anything but a tubing micrometer to measure neck thickness you're wasting your time.

Measuring to a tenth, i.e., 0.0001" is not easy and really requires a temperature controlled environment, but measuring to ± 0.0002 or 3 isn't that big a problem as long as you keep the temperature more or less constant.

As I mentioned before necks that are ±0.0005" (five ten thousandths) then a properly sized neck bushing doesn't require expanding after sizing.
 
I checked neck wall thickness with a RCBS case master it measures in thousandths. I do not have a regular tubing mic..I need one
 
With a dial indicator that only reads to 0.001 there should still be no movement or very little wiggle of the needle around the case neck. Any more than that shows that you're either going too fast, or there's another problem in your neck turning operation.

I'm not trying to be a pain in the tail, but just trying to point out that unless the job is done right it's only wasting your time.
 
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