Gents,
its time for me to learn the finer art of headspace "adjustments".I might very well be confused from past readings,so allow me to make provocative statements that very well might be wrong.
My major concern would be:
1:head seperation from headspace too long in the chamber
2:chambering reloads,fired in same gun.

My current policy is to necksize only,this in order to limit unnecessary brass movement from squeezing the brass in a FL die and expanding it again in the chamber during firing.

My understanding is that a rifle has a fixed headspace in its chamber.This length should be nominal but may not be,so it might be worthwile to measure it after firing? And if different than nominal adjust the die in yet unspecified ways.

A result of my above statement,would be that if always fired in the same rifle/chamber there is never a need for FL sizing the brass.
In reality,chambering gets sometimes sticky after ~ always necksizings.
Even if brass starts out to be "odd"size or shaped,after 1 firing,assuming the chamber is concentric,the brass would be "fireformed" for that chamber and would never need "adjustments"by dies.
Another statement would be,that occasionaly only the OAL would need trimming back,from elongation of the neck.

Now to the contrarian statements ,not explained by above,maybe idealized condition.

If above is all true:
1 why do we have head seperation at all?
Obviously the brass is flowing forward,not stopped by the shoulder?

2 Why do I "need" a head space gauge to measure same,assuming the rifle chamber is constant.
3 Why do I read recommendations of :bumping the shoulder back" "a little" "by feel" to apparently adjust for a shoulder that is too far forward,meaning the rifle chamber is too large?
the headspace too long?

after we digest the theory,we should then be able to intelligently prepare our brass for reloads.
1 neck sizing
2: occassional FL to address fudge realities?
3 if different for rimmed brass,how so?
thanks for staying with this long note

sheephunter

I have made it a practice to neck-size all my bottle-necked cases. In addition, I only size 1/2 the length of the neck.

Once the brass is fired in a particular rifle, that is all that is necessary. I have cases which have been fired 40 times or more and NEVER full-length sized.

Cases are trimmed about every 5 loadings.

As for the brass flowing and the shoulder "stopping the brass from flowing", it doesn't work that way. If you dig a ditch, and put several 40-degree turns in it, and then fill it with water, does the water refuse to go around the turns? Nope...

It is the same with brass.

Ditto riciardelli. A rifle has a "fixed headspace in its' chamber", as you say, but what happens to your case when fired depends upon how rigid your breech lockup is. If you are shooting a rifle that has a rear lockup, like some lever actions or the British SMLE, there is a tendency for the case to stretch some each time it is fired. This stretching causes the case to be thinned out just ahead of the web. The more times the case is fired, the thinner it gets, and eventually the head separates. With a "springy" action, this is going to happen no matter how you size your cases!! If you are using a gun with a solidly locked-up breech, like a Mauser-type bolt-action or falling-block single-shot like the Ruger No. 1, this does not happen, as long as you did not set the case shoulder back in the resiziing process. Therefore, your cases will "last forever", as long as you load to reasonable pressure levels AND DON'T SET THE CASE SHOULDERS BACK while resizing them. If it becomes necessary to full-length resize your cases occasionally, (and it may), OR YOU DECIDE TO USE SOME BRASS FIRED IN A DIFFERENT CHAMBER, take a lubed case, and, using a kitchen match, smoke the shoulder and neck with carbon black from the match. Then adjust your full length resizing die to the poin that the shoulder of the die just barely "kisses" the shoulder of the case. This will resize your case sufficiently, but not enough to set the shoulder back too much.

Thanks for the simplification.Thats what I understood the facts to be.My "confusion" coming from my readings to have to worry about/measure my headspace,setting shoulders back once in a while.
I am only using bolt action rifles,and therefore assume the chamber/head space to be a constant.
I only necksized like ricciardelli,though I can improve on that too by limiting that to 1/2 neck length,thanks ricciardelli.I presume the 1/2 length would actually be bullet seating depth into the neck?Your ditch analog is very graphic and useful to remind us how brass flows forward.

SO if I understand this correctly,I dont have to measure headspace with a gauge,or bump the shoulders back - ever,given I only use brass fired in same gun.

Expounding on eldeguello's description of FL resizing:
I usually screw my dies down to touch the shellholder,implicitly assuming that the die's headspace is the same as my rifle's.
I should really compare the two ,as outlined for instance with the smoked shoulder/neck,thereby adjusting for a rifle headspace that is longer than the headspace in my die?
Another fact from these explanations would be,
never to shorten the cartridge's headspace more than the rifles headspace,which seems obvious.
Now,taking this treaty full circle:should my rifle's chamber have a headspace shorter than in my die ,I guess I would have to "bump the shoulder back" though I could not do that with the die (?) because its headspace is too long.

Maybe the need for "bumping the shoulder back" comes from the fact that with the brass flowing forward,in time we are getting a perfect fit of cartridge and rifle headspace,which is too tight for chambering the load?

Are the spacers to be used under the resizing die,I guess thereby allowing for a longer headspace of the cartridge?

Thanks for the interest

sheephunter

I agree with all and I use the burning match to set my dies...

However I full lenth resize all my hunting ammo, I want it to slop in and not kiss anything, I also run it thourgh the gun..but I will probably be hunting dangerous game..that said I prefer proper feeding and function to accuracy in a hunting rifle....Full lenth ammo seems to last about as long as neck sized stuff in a "good" chamber or so it seems in my rifles and it is about as accurate. I doubt that I lose more than a 1/8 of an inch or less by full lenth resizing..

I neck size on varmint and target guns most of the time.

Western, simple. Use the match to blacken the shoulder area of the case. Then, screw in the die in a little at a time, until the black on the shoulder shows the die is touching on about 50-70% of the shoulder. At this point, you are setting the shoulder back "a couple thou", which, IMNSHO, is the best of all worlds. HTH, Dutch.