SmallCaliberCentral

it would not at all surprise me if everybody already knows what i have learnt today but i thought i would ask for experienced peoples opinions on this.my full length die makes a lot of noise when the expander pulls back through so sunday morning when the wife was still asleep i decided to just neck size.last time i tried neck sizing my groups opened but i thought i would give it another try.i also decided to weight sort my fully prepped brass.to every .1 of a grain.
off i went to a field and started at 100 yds i set up the chrono and here is my result

case weight 97.5 grn shot 1 3232 fps
2 3180 fps
3 3163 fps

case weight 98.7 grn shot 1 3316
2 3352
3 3283
mmm i thought the heavier the brass (thicker walls more preasure) the faster the bullet.i then picked two bullets either end of the spectrum

case weight 96 shot 3163 fps
case weight 99 shot 3397 fps
this confirmed what i suspected.
the last time i fired my pet load i was getting 3450 fps so i would think that because i only neck turned the case preasure was less so i lost 125 fps approx.
i should add that i started a new tub of rl 15 today and as soon as i did my charger through heavier loads how the heck does that work.
if you guys could confirm that this is what happens with only neck sizing and brass weights it would save me running the tests again.
thanks for your input chaps.
pics are not great but i did not want a drill seargent shouting at me again.

Technically speaking FL sizing should require a tad more powder to get back in the node. Energy is expended on pushing the brass outwards towards the chamber walls. In my 6 ppc its usually .2 gns extra to find the hotspot.
That rule need not be chiseled in stone. Many variations between neck tensions between a FL and necksizer could easily negate that.
In the ppc I use the necksizer in conjunction with a body die. Neck tension remains the same throughout.

If your FL die expander ball is making noise your not lubing the interior necks adequately/correctly. Its OK to feel it but not hear it.

Different lots of R-15 can have different velocitys. Beyond that I have no idea what you were trying to convey.

With a mild load such as that you can necksize indefinately. I turned my necksizer into a shoulder bump die. I only NEED to FL when running hot loads on well used brass. I generally FL every firing just to keep things consistent.

Your brass weights seem to indicate heavier brass shoots faster. Thats the theory.
In the 204 I shoot Nosler. Everything else gets Lapua. I sort nothing.
I've found over the years its cheaper to buy something I have confidence in as opposed to running multiple tests for every load I happen upon.

Very nice field

Technically speaking FL sizing should require a tad more powder to get back in the node

mmm i found the opposite,the case has expanded so just neck sizing leaves more volume in the case.
full length sizing reduces case volume = more preasure ?

shocked me today the difference it made,30 mph wind here at the moment but hope to get out again soon.
thankyou for the reply.

A neck sized case does have more volumne on the reloading bench.

Once the triggers been pulled one of the first things (hopefully) to happen is your brass expands to fill the chamber. That requires energy. Pressure is siphoned away from the base of the bullet to move that FL sized case a smidge more than necksized brass.
How much? Way to many variables to answer.

I've seen loads that remain constant in the 204 between FL and just necked. If one shows a more accurate tendency I'll go with that.
Theres a thousand variables that could change the cause and effect. Consistency is the only key. good Luck.

a step back is in order,return to full length for me.if it returns to my pet load speed or not i will post findings.