Full length sizing sets back cartridge dimensions such that they will fit any chamber in a given calibre.

From what I have read about the subject, neck sizing once fired cartridges produces custom fit brass for that given chamber and is said to be beneficial on accuracy.



With my RCBS FL dies, I set back the neck no more than needed to seat the bullet. The shoulder is not touched, but the case body shows marks of partial FL sizing.



The cases I have sized in this way are easy to chamber and extract after firing. Some chamber with a very slight throat contact, felt when closing with a stripped M98 bolt. Some cases show a very thin rub mark on the casehead just on closing, not on extracting fired cases. I trim all my cases to max. dimensions every time I reload them.



To me this means there is little or no clearance with these cases in the 30-06 chamber they are meant for.



Is this a safe procedure or should I really set back the shoulder a few thousands?



If this is not safe, in what way does resizing with neck sizing dies differ from FL sizing?

As long as you're trimming your brass for length you are totally safe. And if you are getting low runnout numbers you are getting every advantage of necksizing.

You are doing what is called partial FL sizing" and it's the recommened proceedure for your die. If one brings the FL die all the way to the shell holder then the case is returned to SAMMI dimensions at least in theory. Things vary and function is our primary goal.

As you might imagine there are cartridge dimensions and chamber dimensions and they are not the same. The chamber must of course be larger so the case will enter.

There is much to this. For average guns most of us are better off FL sizing the case so it enters freely. For match grade chambers or just good factory chambers other methods will work well also.

None of us should size a case too much. This could result in early case head separations. The bottlenecked belted cases are an extreme example of this as their chambers have to clear the shoulder by more than what rimless chambers do.

I started using the Redding body dies this year in three differenbt calibers. That gets my shoulder bumped back, then I use a neck die to finish the job. I've had a couple of rifles lately that blow out the shoulders so I can't do the job with my neck sizing dies. This new method seems to work very well for me. Just one mans opinion. Best wishes.

Cal - Montreal