Re: Resize brass that still fits in chamber ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">aloreman...I still disagree. When you full length size your brass you are sizing all the way down the body, and the case lengthens. The brass has to go somewhere. When you neck size only, the case doesn't lengthen measurably. So, WHY should you lengthen the case and trim it back each time when you don't HAVE to do so? If you have to bump the shoulder each time, then do so. If you don't...then WHY do it? </div></div>
You are, of course, correct that any amount of sizing will cause brass flow.
The cause of CHS's is brass thinning at the web, which is <span style="font-weight: bold">predominantly</span> caused by excessive headspace. The firing pin forces the case forward, there is a pressure rise, case grips the chamber, and the ass end of the case stretches rearward until it contacts, and is supported by the boltface.
In that case, ALL of the stretch, and associated brass thinning, is focused right at the caseweb...in the worst place possible.
While it is true the brass will stretch/thin everywhere, including at the web while FLSing, it is minimal.
Still, assuming you're running well within SAAMI pressure limits, are using quality brass, never loose your brass, never set the shoulder back too far, and routinely anneal casenecks to avoid splits...you are correct in stating that FLSing will wear brass out faster than NS only, and the occasional shoulder setback.
My understanding is benchresters set their neck clearance so precisely that brass springback allows them to reload cartridges with NO sizing at all. I'm not a benchrester though. I am a field rifleman, and my ammo just has to WORK.