Why FL resize?

[Leo_B]

Ok, I admit y'all lose me about half the time talking in graduate level while I'm barely a first semester freshman. And yes, I'll only be shooting anything I load in one gun, at least for now. In my lack of knowledge I thought neck sizing extends the life of the brass. And that now and then you need to FL. So I was thinking NS 3-4 times then FL once then repeat. It's beginning to sound like the easy way out is just FL size every time.

 

[Rob01]

So I was thinking NS 3-4 times then FL once then repeat. It's beginning to sound like the easy way out is just FL size every time.

Now you’re getting it.

 

[ELR LVR]

Ok, I admit y'all lose me about half the time talking in graduate level while I'm barely a first semester freshman. And yes, I'll only be shooting anything I load in one gun, at least for now. In my lack of knowledge I thought neck sizing extends the life of the brass. And that now and then you need to FL. So I was thinking NS 3-4 times then FL once then repeat. It's beginning to sound like the easy way out is just FL size every time.

Neck sizing only was more to preserve brass life
When guys bought 220 russian and spent countless hours, neck turning, and uniforming every single piece of brass to be exactly the same for 6PPC benchrest, they did not want to loose any brass.
Their chamber tightness allowed for them to not have to FL size.
But caused other problems such as clickers if you ran them too hot.
---
You can neck size only, for a few times.... until you are forced to FL size eventually anyway.
it is just much easier to ensure your cases chamber easily every time by FL sizing and barely bumping the shoulder back .001" - .002"
---
FL sizing will also cause the brass length to grow approx .002" - .005" upon each
FL resizing , requiring trimming
Another reason guys may choose to neck size only so they can go a few loadings without having to trim
Even with that - most of us still choose to FL size and trim
---
You can choose to trim every 2nd or 3rd resizing depending upon how much your brass grows in length.
But keep an eye on it, since if it grows too much it will pinch the bullet upon chambering and drive pressures up to unsafe levels. A chamber may only allow .030" neck growth before this happens.
Some may be less, I have heard of them pinching when .020" over book length.
The loading manual will give an OAL to trim your brass length to
it is ok to trim it back a little further, such as .010" more than what the book specs out.

 

[Oldbloke]

Yep, easier to FLS everytime, just do as little as you can. Trim as required.

 

[KMW 1954]

As long as we are still going at this.

I generally shoot just two rifles. A Savage Model12 223 and a Shilen Match 6ARC..

I have shot these enough to get very good and consistent numbers on my brass to set up my sizing die to get the maximum from it. To do this I measure each batch with a Hornady comparator to start and record the shortest and the longest lengths. I then shoot it with mid-range loads and when finished I measure again with the comparator, again noting the long and short.

From there I take the longest cases and size then to a .001" set back and then drop them into a Lyman case gauge to see how they fit. Still too long or too short. If they are not to long and at least flush with the case gauge I then resize everything to that length. And yes when finished some are short of the Longest and have not been pushed back. I then reload them all and repeat this same procedure.

After a few firing I find out what the fired length of this chamber is using the comparator and bump back .001". Also by doing it this way I find I can get about 5 firing from each before I have to trim them back. On the issue of trimming, when I trim my brass many manuals recommend trimming back about .010" or there abouts. I trim back just .005" from max.

So from this I surmise that my brass is stretching very little upon each firing. So as we need to run our brass thru a sizing operation anyways, why not just full length resize it to a minimal amount.